The Basilica of the Assumption of Our Lady of Lekeitio (la Basílica de la Asunción de Nuestra Señora de Lekeitio) is a Gothic style church with a basilica floor plan distribution. The Basilica comprises three naves of different heights, the central of which is twice the height of the lateral naves, and four sections that originally had a chevet with three polygonal apses. The place of worship was built on the remains of a previous building that had burnt down in 1442. Most of the construction work had been completed around 1487.
The sacristy was built towards the end of the XVI century and, mid-XVII century, the old portico that was later relocated to the Dominican Convent in the same town was also built. During reformation work carried out by Casto de Zavala around the end of the XIX century, the Basilica was given a an ambulatory and a new portico on its northern side and the sacristy was relocated.
Among the many interesting pieces of furniture contained by the temple are the main late-Gothic monumental altarpiece that dates from the beginning of the XVI century, the Romanesque figure of the Virgen de la Antigua, two Flemish-style coffin lids and the Cavaille-Coll organ.