In houses upkeep matters more than age. 2 out of 3 buildings I lived in are about a 100 years old (not present in map surveyed in 1914, present with right house numbers on map surveyed inbetween 1920 and 1924), and my current flat is in a 75y old building. Reinforced concrete skeleton, and the rest is brick. Best flats I ever lived in, the brick structure dampens the sounds well, and the high ceilings/tall windows let in a bunch of natural light.