In brief
Old Nessebar is not an architecture of a moment. Ancient remains, medieval churches and later houses exist in a common urban environment.
Useful to know
To read the old Nessebar, separate the historical layers, instead of looking for a single "style of the city". UNESCO describes ancient remains, the medieval Old Metropolis and 19th-century wooden houses as parts of the rocky peninsula's heritage. [1]
This means that adjacent buildings may belong to different periods and have had different tasks. The religious building, dwelling and fortification should not be evaluated as variants of the same facade composition.
A practical task when viewing photos is to find one example of a church, a house and a remnant of a fort. Record what you see and what you know from the source separately. Only appearance does not prove the exact date of each individual wall.
The material is for the architectural reading of the city. It does not give up-to-date opening hours, entry conditions or a route to access each monument.
Sources
For further detail and to check the information: