Amsterdam's oldest church is not regularly used for services anymore, but it still feels holy. It has been rebuilt over the years, but the most stunning thing is its wooden ceiling, parts of which are (relatively) original, and the paint still glows a bit way up in the gloom. Inside the church, you really get a sense of the city's old, old seagoing past, and all kinds of explorers and sea captains are buried under the stones. The space is typically used for exhibitions, and sometimes you might catch an organ concert. With separate admission, around the west side of the church, you can climb up the tower and look over the old town, which is a great view.