IOTL significantly more historic buildings were lost in peacetime than in war. Prior to OTL's 1970s the idea of urban heritage conservation was next to non-existent, entire quarters had been levelled to build impressive new boulevards and create wide new squares as early as the 1860's, medieval monasteries were torn down to build department stores, old city halls were happilly demolished to be replaced with new, more spacious and representative ones which would fall victim to the same procedure a couple of decades later. A continued peace would have led to a lot more capital being available in Europe of which a good part would have been invested in real estate. And while a part of those investments would have been used to build up previously undevelopped areas, a substatial part would have been invested in redevelopment projects in the city centres. Investors would consider those low old buildings unprofitable and want to replace them with new, higher ones. And the up and coming architects of the time they'd hire and the city planners that would grant them permission to carry out their plans had developped a real hate boner for historic buildings, going as far as to call their decorative styles of centuries past a crime and beautiful old town centres "clogged up with old junk that should be put down, the earlier the better". Without the World Wars we might have ended up with fewer surviving old buildings, especially in eastern Europe, since IOTL the money simply wasn't there to build new ones. Had e.g. the Great Depression not interfered, Prague's New Town embankment might have been "rejuvenated" with up to 20 floors high modernist buildings according to the plans of my grand uncle in the early 1930's. Just to give an idea of how much he disliked everything old and decorative, he had inherited an art nouveau style house and the first thing he did was to modernise it by having all the typical art nouveau decorations chipped off, the art nouveau windows torn out and having it remodelled in the then popular new objectivity style with a white, tiled facade. And even where single historic monuments of sufficient importance were to be preserved, it, more often than not, did end up the way of the then newly finished Cologne Cathedral, where the surrounding buildings, most of them dating back to the medieval, renaissance and baroque eras, had been demolished in the 1880s and 90s to grant an unconfined view of the monument from all directions.