The church owes its name to the discovery of a carved image of the Virgin in the reeds growing along the banks of the estuary in around the year 1400. Construction was begun on the current building in the 16th century. The church has an open plan, with three naves and an apse. The tower stands at the foot of the building. Highlights of the interior include the altarpiece of the Virgin of El Juncal, a 17th-century work by Juan de Bazkardo. It was declared a National Historical and Artistic Monument in 1973.