Heiligenkreuz Abbey, also known as Stift Heiligenkreuz, is a Cistercian monastery located in the village of Heiligenkreuz in the Wienerwald (Vienna Woods) region of Austria. It is one of the oldest and most significant monasteries in Europe, and it has played an important role in the cultural and religious history of Austria.

The monastery was founded in 1133 by Margrave Leopold III of Babenberg, and it was the first Cistercian monastery established in the region. The abbey quickly became an important center of learning and scholarship, and it played a key role in the spread of Christianity throughout Austria.

Heiligenkreuz Abbey has a rich architectural history, with buildings from a variety of periods, including Romanesque, Gothic, Renaissance, and Baroque styles. The monastery's most notable building is the Romanesque-Gothic church, which dates back to the 12th century. The church is renowned for its beautiful architecture, including its impressive cloisters and stained glass windows.

In addition to its religious and cultural significance, Heiligenkreuz Abbey has also been an important center of education throughout its history. The monastery has a renowned school of theology and philosophy, and it has produced many distinguished scholars and theologians over the centuries.

Today, Heiligenkreuz Abbey remains an active Cistercian monastery, and it continues to be an important center of learning and scholarship. The monastery is also a popular tourist destination, and visitors can tour the beautiful church and cloisters, as well as enjoy the picturesque surroundings of the Wienerwald region.