Stadtburg Andernach

The castle occupies a compact, parallelogram-shaped plot at the southeast corner of the contemporary city wall and was built as a moated urban fortress. Its principal fabric shows a Romanesque core with later Gothic and Renaissance interventions. A system of inner and outer walls sat within a broad water-filled moat that surrounded the complex.

The keep, the oldest substantial element, dates from the original work in the late twelfth or early thirteenth century. Originally three storeys high, it was raised to four storeys in 1496. The keep later took a baroque roof profile by the eighteenth century and from 1838 has carried a low, flat tent roof, giving it an overall height of about 30 metres. Inside, the second upper floor received stone vaulting during the late medieval period. The keep remains the most complete building on the site and has been reused for prison functions, for hostel accommodation in the twentieth century, and for registry ceremonies on its third floor.

Four corner turrets survive as part of the defensive outline, each providing platforms and a protected walkway. The north turret retains its pointed, low tent roof. Between the keep and the southeast powder tower a continuous west-facing wall unifies several residential and service buildings; this wall is punctuated by large windows set in basalt frames with basalt window crosses, a careful masonry feature of the later phases.

The main residential range and inner gatehouse form a connected sequence on the south side. A two-storey gatehouse linked the castle garden to the western forecourt and to the adjacent main hall. The hall complex included a narrow forebuilding and a larger block that projects into the courtyard and rises to a triangular gable above the roofline. The preserved west wall of this range still shows evidence of window sills and fireplaces. A three-storey stair tower with a conical roof stood at the projecting northeast corner and provided the principal internal circulation.

On the southeast corner the massive round powder tower was built in 1519 and served as both a castle tower and a defensive point on the city wall. The tower measures about 18 metres in height. It underwent repair in 1980 and received a new flat conical roof in 1981 that takes its form from a seventeenth-century model. A decorative trefoil frieze in tuffstone runs beneath the upper windows of the powder tower and continues along the keep and adjoining residential buildings.

The castle’s water defences included an external moat described as over five metres deep and as much as thirty metres across. Internally the site contains a broad ditch running north–south along the line of the powder tower, the palas and the keep’s west wall; this internal trench measures roughly twenty metres wide and five metres deep. A substantial stone access bridge links the garden to the inner gate; this four-arched masonry bridge, about twenty-three metres long, survives intact.

The medieval east gate complex, today called the Koblenzer Tor, survives as a four-storey double-gate ruin. It stood with a drawbridge, a flanking moat, a portcullis and corner turrets and retains the monumental scale of a purpose-built city entrance. Much of the surviving masonry shows use of basalt for window surrounds and the application of tuffstone trefoil ornament beneath rooflines. Some ancillary buildings once carried timber-frame upper storeys, notably in the former stables and remises. Roof renewals and conservation work carried out around 1980–1981 repaired the powder tower and refreshed several tower helmets, while the keep’s nineteenth-century roofline remains visible today.