The Church of San Nicolao in Portomarín, formerly known as the Church of San Xoán de Malta, is an impressive structure that combines religious and defensive functions, built between the 12th and 13th centuries.

This church is characterized by its unique, slender five-bay nave, where the bay closest to the apse is covered by a ribbed vault, while the remaining bays have pointed barrel vaults. The bays are separated by transverse arches resting on embedded columns. The semicircular apse is covered by a quarter sphere, and the straight bay preceding it has a barrel vault.

Lighting inside comes from two rose windows, one on the western façade and another above the arch leading to the apse, as well as windows in each bay and in the apse.

From the outside, the church resembles a fortress due to its strategic position along the Miño River. It was intended to serve as a castle for the Order of Saint John of Jerusalem, in addition to being a church. Consequently, it features a tower at each corner of the nave, connected by a parapet walkway running along the entire perimeter, topped with battlements, just like the towers.

Construction likely began in the late 12th or early 13th century and was completed in the first quarter of the 13th century.

Despite its solid and austere appearance, the church’s three portals are richly decorated. The main portal, on the western façade, and the other two, in the fourth bay of the nave, contrast with the structure’s sobriety. The tympanum of the main portal depicts the 24 elders of the Apocalypse surrounding Christ Pantocrator. The north portal depicts the Annunciation, along with figures of sirens and beings with bird bodies and human heads. The south portal features three human figures: Bishop Saint Nicholas and two men holding a crozier and a book.

In 1962, due to the construction of the Belesar reservoir, the church, along with the Romanesque portal of the Church of San Pedro, was moved to the new town of Portomarín, atop Mount Cristo.