The heritage complex of Lock 4 at Campos was built between 1842 and 1849 and is located on the Campos Branch of the Castile Canal, within the municipality of Castil de Vela (Palencia), at kilometer 139.850. This site represents an advanced stage of the canal’s development, in which hydraulic engineering was precisely adapted to control water levels, ensure flow safety, and integrate with associated road and service infrastructure. Its overall function was to regulate the water level, allow navigation, and manage the canal’s flow in a predominantly agricultural area.
Lock 4 is a simple, rectangular lock with approximate dimensions of 28 meters long, 5.05 meters wide, and 3.60 meters high. It is constructed of limestone masonry and retains its original hydraulic structure. On the left bank, a fixed-lip spillway connects first at the surface and then via an underground conduit to one of the intakes on that bank, discharging directly into the lock chamber wall; the other intake remains sealed. Downstream, a stone hammer protects the structure from erosion. The lock was later renovated, incorporating a new arched concrete weir with a slab walkway and metal railings, as well as a concrete spillway, and remains in a good state of preservation.
Associated with the lock are several elements that complete the functional reading of the complex: the bridge that crosses the lock and the diversion, built in limestone ashlar with segmental arches, two main and one smaller, which guarantees the continuity of the road and is in a good state of preservation; the old lock keeper’s house, made of pressed brick and a wooden structure, now unused and in poor condition, but with protected facades and structural elements; and a large warehouse aligned parallel to the canal, made up of several modules of rammed earth, brick and stone, currently in ruins, which testifies to the logistical activity linked to the operation of the canal.
A visit to the Campos Lock 4 complex allows one to understand the Canal de Castilla as a complex territorial work, where water, roads and architecture form an inseparable unit.
