The Hamburger Bahnhof is a great contemporary art gallery. I'd been there before in 2004, and loved most of it except the main exhibition. It was the same this time, with huge amounts of space devoted to stuff by Wolfgang Tillmans, which was mostly rubbish. But away from his work there were some excellent things. One installation that I particularly liked was an almost entirely dark room, with just an incredibly faint image projected onto the far wall. You had to spent at least ten minutes in there before the point of it became clear, and I liked that. Re-emerging into the bright gallery, I needed another ten minutes to be able to see properly again afterwards.