The Martinikerk, dedicated to Saint Martin, is the principal church of Bolsward and dates from the late 15th century in its current form, although there was a church on the site from at least the 11th century. It is a three-aisled hall church of brick, typical of late Gothic Frisian construction, with a free-standing tower that leans visibly.
The interior is best known for two things: the carved wooden choir stalls with late medieval misericords, and the great Hinsz organ above the west end. The church transferred to the Reformed congregation after the Reformation and lost much of its Catholic furnishing, but the woodwork and the organ survived. It now belongs to a heritage foundation and is open as a concert and exhibition venue as well as for worship.