Huis te Riviere, Schiedam

The surviving ruins occupy a compact footprint approximately 20 by 17.5 metres and consist chiefly of the lower portion of the main tower and the foundations of adjacent walls. The principal tower stood as a freestanding, square keep with a base roughly 12 by 12 metres, set inside a larger almost-square castle of about 45 by 50 metres begun in the 1260s. A small internal moat separated the tower from the nearby buildings at the northwest corner, indicating the keep formed a defended inner position within the wider enclosure.

Beneath the tower a high vaulted cellar survives. The cellar was closed by a barrel vault (a semi-cylindrical vaulted ceiling) and the thick masonry there exceeds three metres in places. Small light openings pierced the walls, measuring only about 12 centimetres on the exterior but widening to roughly 95 centimetres on the interior, a design that admitted light while keeping the basement secure. During construction the eastern side of the cellar settled unevenly and builders corrected the footing by adding a layer of cut bricks to level the floor. Much of this substructure remains in situ.

The ground floor and its fittings reveal domestic and service functions. Ground-floor wall thickness reached about 1.40 metres and the room layout included windows in the south and east walls, with evidence for a west-facing opening as well. A garderobe, or privy, stood on the south side and a niche held a lavabo with a red-stone sink for washing. A fireplace occupied the north wall. Access between levels continued by an internal stair, and painted depictions from around 1574 show a stair feature projecting at first-floor level. Above the first floor the roof was hipped and carried merlons (the solid uprights of battlements), indicating an appearance that combined domestic roofing with defensive parapets. Later openings cut into the masonry now provide direct access to the cellar and to the stair that led up to a northern wing at ground-floor level.

Remains of adjacent wings and the fortified outer courtyard survive as foundation lines and low wall fragments. The wing to the north of the tower measured about 8 by 17.5 metres, while a southwestern compartment measured roughly 12.5 by 5.5 metres. Foundations and historical depictions show stepped gables facing west on the northern and southwestern ranges, and a painted view around 1574 corresponds with that arrangement. The curtain wall that surrounded the inner castle survives in parts and shows internal buttresses placed very close to the main tower. Similar stretches of wall appear on the western edge of the forework, and masonry traces show the enclosure wall projecting into the surrounding water in places.

Building materials and workmanship record changes in the construction sequence. Foundation bricks are generally about 28 centimetres long and 7.5 to 8 centimetres thick, with occasional examples reaching 31 to 32 centimetres. Above the basement the brickwork is predominantly red, while lower courses include many yellowish bricks, a contrast that marks a break in building phases. Interpretations of the early plan include a central keep linked to a ring wall, a slightly skewed corner tower, and the possible presence of a covered walkway or bridge between the keep and another tower. The forework shows parallels with contemporary fortified courtyards elsewhere in the region, and a historic map depicts a connecting passage between the main castle and an adjoining court.

Today the ruin stands as a fragmentary remnant of the medieval complex, the upper parts of the tower having been removed in 1574. The masonry sits adjacent to the municipal town hall complex, which was extended close to the site, and the remains can be seen from public roads. Excavations in the 20th century uncovered plan details of the tower and parts of the outer courtyard and informed later conservation and town-planning proposals for the surviving fabric.