I'll try to cover some of Italy's top missing sites:

Padova Urbs Picta (possibly one of Italy's top WHS)
Volterra
Parma (I'd suggest a serial nomination of baptistries with the likes of Cremona, etc.)
Alba Fucens in Abruzzo
Aosta
La Maddalena transnational site with Corsica
Asinara
Sammezzano Castle for Moorish revival
Ascoli Piceno
Bergamo
Bologna
Rocchetta Mattei blend of eclectic styles
La Scarzuola Ideal City
Civita di Bagnoregio
Castelgandolfo
Romanesque Cathedrals of Puglia (Otranto above all)
Via Francigena

The Wikipedia article mentions it is already part of the "Golden Mountains of Altai" WHS. The nomination file mentions them as well.

But only in the buffer zone, as stated by the text on the TWHS page?

Hebrides Islands, UK
Type: M
OUV: From the scenic mountains of Skye to the Tweet traditions of Harris, the Hebrides are a special cultural place.

Whisky Distilleries of Scotland, UK
Description: So many distilleries cover Scotland. Some of those are really scenic.
OUV: What is more Scottish than Whisky?

Scottish Castles, UK
The Scottish Highlands are covered by clan castles. Most prominent Eilean Donan Castle. But plenty to choose from.
https://historiceuropeancastles.com/best-castles-in-the-highlands-scotland/

St. Andrews Gold Course, UK
OUV: Home of golf in one of the nicest old towns of the UK.
"The oldest and most iconic golf course in the world. The Swilcan Bridge and Hell Bunker are recognised across the globe, yet the greatest feature of the Old Course is that despite its grand status it remains a public golf course, open to all."
https://www.standrews.com/Play/Courses/Old-Course

Historic Football Fields and Stadiums of the UK
OUV: Home of football. Question is how much tangible heritage remains.
https://www.football-stadiums.co.uk/articles/oldest-football-stadium-in-the-world/

Pubs of the UK and Ireland
OUV: Outside Japan the oldest companies still in operation are in the UK. These are well and seemlingy accurate preserved and such a distinctive feature of the UK. Simply strolling around London you will stumble into so many nice old pubs... Ireland included as the pub culture seems equivalent.
https://www.oldest.org/food/pubs-england/
https://tbexcon.com/blog/oldest-pubs-in-ireland/

University of Manchester - Computer Science Department, UK
OUV: So much computing history originated in Manchester, with Alan Turing the most notable figure. But I can't judge how tangible the site is.
https://www.cs.manchester.ac.uk/about/history-and-heritage/history-in-depth/index.htm

Aran Islands, Ireland
OUV: Stunning island landscape facing the Atlanic with Dun Aonghasa the most notable tangible heritage.

Clonmacnoise, Ireland
OUV: Most iconic Irish monastery ruin. Stunning.

Belfast Murals and Fortifications, UK
OUV: Remannts of a bloody civil war.

Full name of site: Salento and the "Barocco Leccese"
Country: Italy
TWHS?: yes (see title)
Short description of site: (Unesco site) The distinctive character of the Salento peninsula comes from a series of architectural achievements associated to an artistic phenomenon known as Barocco Leccese, which developed in Lecce, Salento's historical and artistic centre, and in Terra d'Otranto between the second half of the 16th century and the end of the 17th century. The 'Barocco leccese' developed in the framework of the Counter-Reformation in response to the Church's need to re-assert its authority, mainly through an ostentatious display of power. Its distinctive, autonomous style can be found in the particular, imaginative and suggestive combination of architectural elements on the façade: porticoes, windows, balconies, loggias, gargoyles, corbels, festoons, columns and cornices crowded with human figures, flowers and animals. The expressiveness of these decorations overflows into the strictly religious areas and can be found also on altars, ciboria and calvaries.
Criteria: Cultural

Different periods. Chicaco was where the skyscraper was invented. New York City was were in the 1920-1930 it reached its epitome.


Main reason: I was proposing a mixed site, not a natural site.
* Stockholm Archipelago is urbanized, so not a natural site, but mixed. Pretty stunning to see how Stockholm grew out to the islands.
* Alands are also settled. And date back a long time:
"Members of the Neolithic Comb Ceramic culture started settling the islands some 7000 years ago, after the islands had begun to re-emerge from the sea after being pushed down by the weight of the continental ice of the latest ice-age. Two neolithic cultures met on Åland: the Comb Ceramic culture and the later Pit-Comb Ware culture which spread from the west.[citation needed][18]"
https://en.wikipedia.org/wiki/%C3%85land_Islands


Yes. Would limit it to Lecce.


Only site I would second in your list. Some I don't know, but we can't inscribe each and every great old town.

Give a Swede a lousy site and they will turn it into gold – just like a cheap Ikea shelf or mediocre pop song :D

Jokes aside, maybe it is too close and I have been so many times that it is difficult to see why it would be so special. Beautiful archipelago it is with beautiful summer cottages, for sure.

Yes, you are right. But Golden Altai is natural and this would make the site a mixed one.

This idea has my full support. It is original and convincing.

First of all, some proposals from Nordic Countries:

The Lofoten islands (T) Norway
Wikipedia | Google Image Search
Description: Lofoten is known for a distinctive scenery with dramatic mountains and peaks, open sea and sheltered bays, beaches and untouched lands. The region has unique qualities associated with its marine resources, geology, plant and animal life, cultural monuments and exiting scenery. The birdcliffs are among the largest in the Nordic countries and have earned an international reputation. The area was settled very early, contains many unique cultural monuments.

Svalbard Archipelago (T) Norway
Wikipedia | Google Image Search
Description: An Arctic archipelago (total land area ca 62 700 km²), approximately 60 % of which is covered by snow and ice. The natural biological diversity and the ongoing ecological processes are largely intact. Svalbard can be regarded as the largest and least disturbed wilderness area in Norway. Polar areas are, in general, poorly represented on the World Heritage List. Thematic studies of mountainous areas on the World Heritage List also single out Svalbard as one of 28 candidates with potential before the theme is covered.

The Architectural Works of Alvar Aalto, (upcoming TWHS: serial, transnational)
Alvar Aalto, Wikipedia
Architecture, Alvar Aalto Foundation
Description: Alvar Aalto (1898-1976) enjoyed an exceptionally rich and varied career as an architect and designer, both at home in Finland and abroad. The span of his career, from the 1920s to the 1970s, is reflected in the styles of his work, ranging from Nordic Classicism of the early work, to a rational International Style Modernism during the 1930s to a more organic modernist style from the 1940s onwards. It was characteristic of Aalto to treat each building as a complete work of art – right down to the furniture and light fittings. Throughout his career, Aalto was presented internationally as the 'humaniser' and 'naturaliser' of a cold, overly rational modern architecture. The proposal includes many themes that the World Heritage Strategy calls for, such as cross-border serialization, modern architecture and the 20th century.

Turkey has a lot of potential:

Iznik (T) Turkey
- Iznik (Wikipedia)
- Nicaea (Wikipedia)
Description: Known as Nicaea since ancient times. İznik bears exceptional witness to the introduction and early expansion of Christianity. The city hosted the two of the most important ecumenical councils recognized by all churches. During the Ottoman Empire, İznik gained a world-wide renown for the second time as the centre of production of ceramic tiles, one of most beautiful and enduring types of Turkish-Islamic art. The city is surrounded on all sides by 5 km of walls about 10 m high. Hagia Sophia of İznik is where the Second Council of Nicaea met in 787.

Ancient City of Kaunos (T) Turkey
- Kaunos (Wikipedia)
- Kaunos (Google Image Search)
Description: Founded in the 9th century BC, Kaunos was an important Carian city and sea port by 400 BC. On the border with Lycia, its culture reflected aspects of both empires. Best known sights of Kaunos are six rock tombs on the Dalyan river (4th – 2nd century BC). Other archeological sites include the city walls, acropolis with theater, Roman baths, port agora and temples.

Harran and Sanliurfa (T) Turkey
- Sanliurfa (Wikipedia) | Harran (Wikipedia)
- Sanliurfa (Google Image Search)
Description: Harran, ancient Carrhae, was a major ancient city in Upper Mesopotamia. The old city of Harran is situated in a land through which have run trade routes. The city is mentioned in the Bible. It is important not only for hosting the early civilizations but it is the place where the first Islamic University is founded. The traditional civil architecture, mudbrick houses with conic roofs, are unique. Sanliurfa, known as the city of prophets, is full of historic religious, public and civil architectural buildings.

Mardin Cultural Landscape (T) Turkey
- Mardin (Wikipedia)
- Mardin (Google Image Search)
Description: Mardin is a city in southeastern Anatolia. The city is mainly medieval in origin and is situated on the slopes of a rocky hill, crowned by o fortress built on its citadel. The city as a whole with its traditional stone, religious and vernacular architecture and its terraced urban pattern is the best preserved example of Anatolian soil. Deyrulzafaran Monastery is one of the living religious center of Syriandacobites in Mardin, an impressive architectural complex in the Mesopotamian plain.

A very influential architect. Yes.


I would only back Harran for its history and vernacular architecture. Sanliurfa ist mostly known for its Roman mosaics which have been removed.

Vardzia-Khertvisi (T) Georgia
- Vardzia (Wikipedia) | Khertvisi (Wikipedia)
- Vardzia (Google Image Search)
Description: Vardzia is a cave monastery site in southern Georgia. The main period of construction was the second half of the twelfth century. The caves stretch along the cliff for some five hundred meters and in up to nineteen tiers. Vardzia-Khertvisi, comprising a vast territory in the upper reaches of the river Mtkvari basin is significant in many respects: unique natural conditions contributing to the specific microclimate and landscape, historical context and diversity of cultural heritage. The site includes rock-cut complexes, fortification structures, murals, epigraphical monuments, stelae and chapels.

Cultural Landscape of Canyon in Kamenets-Podilsk (T) Ukraine
- Kamianets-Podilskyi (Wikipedia)
- Kamianets-Podilskyi (Google Image Search)
Description: The dramatic and fairy-tale-like landscape, the castle with great setting and old city with rich history and many ethnic communities make this site unique. Famous attractions include the ancient castle, and the numerous architectural attractions in the city's center, including the cathedral of Saints Peter and Paul, Holy Trinity Church, the city hall building, and the numerous fortifications.

The historical surroundings of Crimean Khans' capital in Bakhchysarai (T) Ukraine
- Bakhchysarai (Wikipedia) | Chufut-Kale (Wikipedia)
- Bakhchysarai (Google Image Search) | Chufut-Kale (Google Image Search)
Description: The historic monuments of Bakhchysarai Valley from the Khan's Palace to the Chufut-Kale represents different phases of the history of Crimea, and especially the culture of the unique community of Crimean Tatars. the Palace of the Crimean Khans, Chufut-Kale town and Salachik complex is a unique example of the urban architecture and is a trace of the engineering capacity of several extinct communities (such as Gotho-Alani, Golden Horde and others) that have once inhabited the Crimean peninsula.

Sites mégalithiques de Carnac (T) France
- Carnac stones (Wikipedia)
- Carnac stones (Google Image Search)
Description: With over 550 megalithic sites scattered across the Carnac region and southern Morbihan, the area is one of the prime megalithic sites in the world due to the sheer quantity of monuments, their size, the singular nature of their carvings and the archeological wealth of the objects found in them – such as jadeite axes. The Morbihan megaliths are the oldest known stone architecture still standing in Western Europe, and thus of value from both a historical and a landscape point of view.

I wish to propose below -

Hecate Strait and Queen Charlotte Sound Glass Sponge Reefs - Sound Glass Sponge Reefs
Antelope Canyon - One of most beautiful canyon
Petrified Forest National Park - Desert
Volcanic and forest areas of Martinique
Sites mégalithiques de Carnac -One of the largest such collection in the world
Minoan palaces of Crete 
Ancient City of Kaunos -Lycian
Wooden Roofed and Wooden Columned Mosques in Anatolia - Typical Antolian style
Oxford and Cambridge -Historic university
Vespasianus Titus Tunnel - one of the world's largest tunnels in ancient world
Mausoleum of Hecatomnus
Theatre and Aqueducts of the Ancient City of Aspendos

I second this.

Some natural proposals, all of which fill a IUCN gap:

Site: Carrizo Plain
Country: USA
TWHS: no
Description: The Carrizo Plain is a large enclosed grassland plain, approximately 50 miles (80 km) long and up to 15 miles (24 km) across, in California. It would be the only representation of the Californian shrubland known for its floral biodiversity and its superbloom. It was supposed to be included in the new American tentative list, but opposition expressed by some of the locals prevented its inclusion. Its preservation is threatened by petroleum production and grazing.
Criteria: natural

Site: South Georgia Island
Country: UK
TWHS: no
Description: The parts of the island that are not permanently covered in snow or ice are part of the Scotia Sea Islands tundra ecoregion. In total there are 26 species of vascular plant native to South Georgia. South Georgia supports many sea birds, including albatross, a large colony of king penguins, Macaroni penguins and penguins of various other species, along with petrels, prions, shags, skuas, gulls and terns. Birds unique to the archipelago are the South Georgia shag, South Georgia pipit, and the South Georgia pintail. The seas around South Georgia have a high level of biodiversity. In a recent study (2009–2011), South Georgia has been discovered to contain highest level of biodiversity among all the ecosystems in the Southern Ocean.
Criteria: natural (although one could include the whaling sites in Grytviken to make it a mixed site)

Site: Alaka'i Swamp
Country: USA
TWHS: no
Description: Alaka'i Swamp is a montane wet forest on the Hawaiian island of Kauaʻi. Although the preserve is home to alpine bogs, it is not a true swamp.It is located on a plateau near Mount Waiʻaleʻale, one of the wettest spots on Earth. It is the largest intact rainforest in Polynesia.
Criteria: natural

Site: Marquesas Archipelago Marine Reserve
Country: France
TWHS: maybe (5564) (As there are no maps in the official TWHS description, I do not if the proposed mixed site with detailed description of its terrestrial nature includes the entire very extensive marine reserve)
Description: The waters surrounding the Marquesas Islands are full of marine life, including various species of sharks, large marine mammals, and sea turtles, with more still to be discovered. In 2012, a scientific expedition in Marquesas found 20 marine species that had not yet been scientifically identified. 11% of the coastal fish and 10% of the molluscs are endemic, making it a one of the most diverse biodiversity hotspot in the Pacific Ocean.
Criteria: natural