Hello guys, I tried to keep up with your work on this list of candidates for the top 50 missing. I was not able to take part in this process but I tried to keep up with your work and I find it very impressive! I don't know if this window is still open for a couple of proposals but I decided to grasp the opportunity before the list is closed. I am not the best expert for natural sites and the ones I would propose are already on your list but I would like to propose two cultural sites if you want to consider them:
Site: Sky City
Description: Acoma Pueblo is a National Historic Landmark in New Mexico. The Acoma have continuously occupied the area for over 2000 years. The Sky City Pueblo is situated on a 365-foot (111 m) mesa and was probably founded in the 11th century, making it one of the earliest continuously inhabited communities in the United States. The 6,000 square feet church Mission San Esteban Rey was build in the 17th century and shows designs representing Christian and Indigenous beliefs. It is a National Trust Historic Site, the only Native American site in that ranking. https://en.wikipedia.org/wiki/Acoma_Pueblo
Site: Sechín Bajo
Description: Sechin Bajo is a large archaeological site containing a circular plaza and a frieze.vRadiocarbon dating indicated that they were constructed around 3500 BCE, making them the two oldest examples of monumental architecture discovered thus far in the Americas, prerunning the pyramids of Caral Supe by almost 1000 years.https://en.wikipedia.org/wiki/Sechin_Bajo
Finally I have one extension proposal, even a multiple one for the Sites mégalithiques de Carnac:
It is not completely clear from the text on the Unesco website but it seems that this tentative sites is limited to the closer area of Carnac and its rows of megaliths. While these are quite overwhelming in size in the effort needed to build them the artistically truely impressive sites are a bit further off: In Locmariaquer, 10 km from Carnac we find a group of Domens and Menhirs dating back to 4000BC, the most interesting being the Table des Marchands with interesting stone carvings. A few of kilometres further east on the island of Gavrinis is the Cairn of Gavrinis of a similar or even older age. It shows the most elaborate, very artistic stone carvings which remind of the carvings in Newgrange but they are even older.
Further away in the northern Bretagne we find another buildings that would deserve inclusion in this nomination or even a separate nomination: The Barnenez Tumulus was called by André Malraux 'The Prehistoric Parthenon'. It dates even further back to 4850 BC, making it on of the oldest man made structures in the world. The cairn is is 72 m long, up to 25 m wide and over 8 m high. It is built of 13,000 to 14,000 tons of stone. It includes also stone engavings. https://de.wikipedia.org/wiki/Table_des_Marchand https://en.wikipedia.org/wiki/Gavrinis