Donjon of Arques
This impressive castle tower may be seen on front pages of many tourist guides to such an extent, that it is a bit surprising, that it really looks as it looks like. It's construction began probably in 1280 and it belonged among Cathar castles. Come to that, there are even such oddities as a "Cathar" hairdresser or "Cathar" funeral service in the region. The castle, however, has at least real historical continuity, which these tourist-traps seem to lack. It was inhabited and reconstructed by a local conservationist some years ago and there is even a small museum today.