What were the main parts of a medieval European city? What were the mandatory buildings there?

There were not so many parts in the medieval city. Firstly, it is a fortified part, a citadel or the Kremlin (in Russia), it was needed in case of war or siege.

Secondly, the trading square (sometimes more than one), the square in front of the town hall, could be a Jewish or Armenian quarter, as well as quarters for artisans – weavers, watchmakers, stone and wood craftsmen. There could be a port – river (Paris, Orleans, Vienna) or sea (Genoa, Venice, Valencia).

Obligatory buildings were the town hall or magistrate, the cathedral or just the cathedral (for Russia – a stone temple, as in Yuryev-Polsky, Grodno or in Kanev already in the XIII century),

walls with towers, a clock tower, a prison, an arsenal.