The Diocese of Bilbao covers all the territory of Biscay, except the exclave of Orduña (between Alava and Burgos), and including the tiny enclave of Valle de Villaverde (Cantabria).

The diocese is divided in seven territorial vicarages: The church was consecrated in Lekeitio in 1287, and was recorded as under construction in 1374.

The neo-Gothic retrochoir by architect Casto de Zavala was added between 1881 and 1884, thanks to benefactor Pascual Abaroa The church consist of three staggered naves in four sections and a polygonal chevet at the centre, the latter surrounded by a lower retro-choir.

On the main wall there is a narrow gallery, in the form of windows with sills decorated with blind tracery.

The archivolted west door is set into a façade blooming with tiny original sculptured decorations.