The architect A. C. Bleys designed this church, built in 1887, with its dark and eerie interior as a replacement for all the clandestine Catholic churches that operated during the Reformation. After the Oude Kerk and "Our Lord in the Attic" chapel, this church became the third and (probably final) Sint Nicolaas church. The all-purpose patron saint of children, thieves, prostitutes, sailors, and the city of Amsterdam, transforms into Sinterklaas in mid-November when he arrives from "Spain" on a "steamboat" with his helper Zwarte Piet (Black Pete). The eve of his birthday on December 6 is celebrated as a family feast when everyone exchanges presents and poems. Note that the church is open only when volunteer custodians are available. It hosts a Gregorian chant vesper service September to June on Sunday at 5.