Opened in 1887, the city's somewhat gloomy, neo-baroque main Catholic church has twin towers and a high domed cupola. At the heart of what was once the old harbor, it started out as a place of worship for seafarers (of whom St. Nicholas is the patron). Inside, murals illustrate themes from the saint's life; the 1345 Miracle of Amsterdam; and the execution of the Catholic martyrs of Gorcum (Gorinchem).