On Wednesday, after workshops and tutorials, the conference organizers set up a trip to Heidelberg. Heidelberg was one of the few cities to avoid being bombed in World War II, so it's still full of old houses and cobblestone streets. The castle is quite old - it was started in the 1200s, though the oldest surviving buildings are from the 1400s. However, it's largely in ruins, having been dstroyed multiple times in the wars between Protestants and Catholics, and by the French.