Buildings last a long time. Don't look for buildings built recently in the period you are concerned with,

. The Normans also brought architecture. I am reminded of a discussion here a few years ago: what's the difference between the Merovingian and Carolinian dynasties in terms of armament and head-wear? The answer was that a figure manufacturer was launching a new range. Anyone that had a Merovingian Frank army did not have to re-recruit in order to wargame 751 AD instead of 750. My point, important buildings last at least 500 years and unimportant buildings aren't attacked.