Hirsau Abbey, Benedictine monastery in Black Forest region, Germany

Hirsau Abbey is a former Benedictine monastery whose red sandstone and grey stone ruins stand among trees above the Nagold. The north-west tower, completed in 1120, has a steep pyramidal tiled roof, tall rectangular windows and a pale clock face near the top; a crumbling wall adjoins it, and further left are gabled buildings with arched windows and a round tower with a conical roof.

Hirsau Abbey grew from a monastery founded around 830 by Count Erlafried of Calw, who installed fifteen monks from Fulda under Abbot Lutpert. After a ruinous decline around 1000, Pope Leo IX ordered its restoration in 1049, and monks from Einsiedeln resettled it in 1065. Abbot William, from 1069, made Hirsau a centre of the Cluniac reform; construction of the Sts Peter and Paul church began in 1082 and it was consecrated on 2 May 1091. French troops burned the complex in 1692.

The name Hirsau derives from the settlement where the abbey stands. Abbot William's reforms, known as the Hirsau Reforms, were adopted by many monasteries, and monks from Hirsau founded Zwiefalten Abbey in 1089. In the left aisle of St. Aurelius Church stands a wooden Spanish Madonna from the early 15th century, holding the Christ Child and pointing to herself with her left hand.

The ruins stand on a plateau on the Nagold side opposite the older St. Aurelius church, which lies across the river; the surviving north-west tower and the walled-up transept openings help orientation. The site is an open ruin with uneven ground, so sturdy shoes help. The Klostermuseum in the adjoining Forstmeisterhof (Calwer Straße 6) documents the excavations carried out between 1876 and 1989.

The north-west tower still standing at Sts Peter and Paul was not part of Abbot William's original plan: the two west towers were only completed in 1120, and they first stood in front of an atrium that received its basilical roof in a final building phase. The nave was thereby extended by 30 metres to thirteen bays.