Lock 9

Lock 9, built between 1759 and 1804, is a simple lock with an oval basin that continues the ascent of the North Branch in one of its sections richest in auxiliary architecture. Measuring 25.50 meters long, 9.60 meters wide, and 3.85 meters high, it is constructed of sandstone ashlar, a resistant material that has allowed the essential structure of the hydraulic work to be preserved. On the right bank, a spillway connects via an underground conduit to the diversion channel on the same bank, discharging against the basin wall before rejoining the canal. From the left wing of the upper entrance, an S-shaped branch branch off, which supplied water to an adjacent building, reflecting the close relationship between the hydraulic infrastructure and its associated productive uses. A small stream also flows beneath the upper edge of the lock through the Horteruelos culvert, an arched structure that facilitated the crossing of the two watercourses. Although its state of conservation is poor, it maintains all of the original hydraulic work.

The complex is completed by several secondary elements. The bridge over the lock, also from the period 1759–1804, features a semicircular arch in sandstone ashlar, with stone wing walls and parapets, preserving the solidity and proportions characteristic of the canal’s engineering. Two auxiliary bridges, also made of limestone ashlar and retaining the authenticity of the original hydraulic work, are preserved at the branch line. These bridges allowed the towpath to continue along the left bank. Next to them is the lock keeper’s house, a single-story building with pressed brick walls, a wooden frame, and a ceramic tile roof. Although now in ruins, it retains original facades and structural elements, giving it considerable environmental value. Nearby stands the imposing San Lorenzo mill, a five-story building (base + four floors) with limestone, brick, and adobe walls, a wooden frame, and a curved tile roof. Its arcade of three semicircular arches, now blocked up, recalls its use as a mill and power station.

Lock 9 is a perfect place to understand the Canal de Castilla as a living heritage, integrated into the territory and full of history.