Abbaye Saint-Cyriaque d'Altorf, Benedictine abbey in Altorf, France

Abbaye Saint-Cyriaque d'Altorf is a former Benedictine monastery whose church, built of reddish-brown sandstone, has a Romanesque nave with a row of small arched windows and a tall pointed portal, a low side aisle, and a Baroque transept and choir rebuilt by Peter Thumb in 1725. A white bell tower with a grey lantern and clock stands to the right, beside a lower pale tower and a red sandstone wall.

Founded in 974, the abbey quickly received imperial privileges and relics that established its importance as a religious center. Over the centuries, the complex expanded through multiple construction phases, each reflecting the evolving needs of the monastic community.

The abbey's main treasure is the bust reliquary of Saint Cyriacus: a 12th-century oak core, partly covered with silver plates in the first half of the 13th century and later with gilded copper medallions. Pope Leo IX brought the saint's arm relic here in 1049, and Cyriacus replaced Saints Bartholomew and Gregory the Great as patron. A 15th-century baptismal font stands in the south aisle.

The church of Saint-Cyriaque stands in the village of Altorf, reached from Strasbourg by the RD 393 towards Molsheim or from the A35, exit Dorlisheim. The abbey buildings are grouped around it: the three-storey 16th-century abbot's house, now the presbytery, linked to the church by a long wing holding the west side of the former cloister, plus the gatehouse and the tithe barn to the west and north-west.

The abbey held minting rights from a concession by Emperor Otto III around 999, confirmed by Pope Leo IX in 1050 and Emperor Frederick I in 1153. Coins bearing the name or image of Saint Cyriacus are attributed to this workshop, which ceased activity in 1296 and was briefly reopened after 1300 before its rights passed to the bishop of Strasbourg's mint.