Dating from 1306, the Oude Kerk is Amsterdam's oldest surviving building. It's also an intriguing moral contradiction: a church surrounded by active Red Light District windows. Inside, check out the stunning Vater-Müller organ, the naughty 15th-century carvings on the choir stalls, and famous Amsterdammers’ tombstones in the floor (including Rembrandt’s wife, Saskia van Uylenburgh). Regular art exhibitions take place in the church; you can also climb the tower on a guided tour. Church admission is by credit/debit card only.