When I went to Osaka Castle, the tour info tells you that the building itself is basically a replica of a castle that was sacked and then rebuilt, multiple time

When I went to Osaka Castle, the tour info tells you that the building itself is basically a replica of a castle that was sacked and then rebuilt, multiple times over the centuries. The inner and outer baileys -- the stone fortifications -- are original, but the castle itself, which was originally made of wood, is brand new in relative terms. The Japanese don't remain attached to their buildings, usually because their buildings have been historically likely to be destroyed by earthquake, typhoon, fire, or invasion. In more recent years, yeah -- houses a few decades old will be knocked down to make way for new developments and no one bats an eyelash, but it's because Japanese culture sort of respects the ephemerality of all things, especially manmade things -- one way or another, any given building is going to fall on a timespan of 30-60 years.