On a small hill above the town of Molins de Rei stand the ruins of the castle built in the 14th century on the ruins of an ancient round defensive tower known as Guadall or Guadallo. This round tower was of Visigothic origin (8th century) and hence was pre-Romanesque. This is confirmed by the remains of a stretch of wall that reuses a section of opus spicatum that was typical of that period. A tower with three storeys is situated on the east façade. This tower still has its door and two openings, one now reconstructed. It is also possible to see traces of the trapezoid floorplan, a small tower built adjacent to the rock, the walls of Guadall Tower and the remains of a large cistern, partly excavated out of the rock and protected by barrel vaulting (10th and 12th centuries).