I'd like to try to find some 'rationale' to base the selection on.
I think we should include at least some cities that were important during the Middle Ages because of size, and have become WHS:
(classified under Urban continuity but 'built in the 8th century' , started to grow over 100,000 in 800)
(is classified as post-medieval, but was 'built' in the 14th and 15th century). Had ca. 94,000 inhabitants
: 165,000 around 1450.
(is classified under Urban Continuity and probably belongs there, but was important in European medieval history as Constantinople). One of the biggest cities throughout the Middle Ages.
(150,000 in 1200)
(is classified as post-medieval, but important parts were 'built' in the 12th) – had 200,000 inhabitants in 1348
(classified under urban continuity but 'built in the 11th century', had 110,000 inhabitants around 1300)
And another angle: capital or main cities representing Medieval Great Powers
- Aachen Cathedral
– representing the Frankish empire (under cathedrals)
– representing the Jagiellon dynasty
– representing the Papacy (under Christian)
– representing Kingdom of Sicily & Normans
– representing Kingdom of Castile (under urban continuity but built in 13th century)
– representing the Medieval Venetian Republic (under urban continuity)
Most of the remaining places in this category (and there are many) seem to have been 'only' regional centers or places of minor importance in their time.