Koln Cathedral Construction, Edited Version, Koln, Nordrhein-Westfalen, Germany, 2015

Most cathedrals in Europe, to the best of my knowledge (I'm not an expert on architecture) date to the middle ages, and as such most are gothic, and perpetually under reconstruction. This is in line with their situation historically, as many took hundreds of years to build. In the case of Koln Cathedral, original construction lasted from 1248 to 1880, although construction was halted between 1473 and the 19th Century (I haven't been able to find an exact date). I don't know much about this restoration, but as I said, it is rare to find a European cathedral without any scaffolding on it.