Vårfruberga Abbey, Medieval Cistercian monastery ruins in Strängnäs Municipality, Sweden

Vårfruberga Abbey is a ruined Cistercian nunnery near Kungsberg farm, about 10 km northwest of Strängnäs. Its surviving grey stone foundation walls outline the original room divisions, and parts of the walls remain. The church was a three-aisled building with short transepts and a low wall separating the nuns' section from the lay area.

A Benedictine convent existed in the 12th century, but its site is uncertain; excavations in 1991–92 found a medieval fortification near the water, possibly the reason the nuns moved to Fogdö church, where the monastery is documented from 1233. In 1252 Birger Jarl and his son Valdemar sealed a letter of protection for Fogdö Abbey, preserved in the Riksarkivet. The nuns moved to Kungsberg and occupied new Cistercian buildings in 1289, when the name changed to Vårfruberga, a daughter house of Julita. Gustav Vasa dissolved the abbey in 1527 and used its stone for Gripsholm Castle.

The name Vårfruberga means "Mountain of Our Lady," adopted when the nuns moved to Kungsberg in 1289. The abbey church was built as a Latin cross with three aisles and a short transept, and a low wall across the nave separated the nuns from the lay congregation. The former monastic church is still occasionally used for open-air services.

The ruin lies by Kungsbergs kungsgård, about 10 km northwest of Strängnäs in Fogdö parish. The low grey-stone foundation walls show the original room divisions; the former abbey church is occasionally used for open-air services. The ground is uneven, so wear sturdy shoes.

The 1991–92 excavations found traces of a medieval fortification on a height by the water, which may explain why the Benedictine nuns left their first site: the fort was probably built there instead. The nuns were women, not monks, and the stronghold was a separate structure, not part of the abbey.