Gregoriou Monastery is an Eastern Orthodox monastery located on the southwestern coast of the Athos Peninsula in Greece. It is one of the twenty monasteries that make up the monastic community of Mount Athos, a UNESCO World Heritage Site and a center of Eastern Orthodox monasticism. The monastery was founded in the 14th century and has been rebuilt and renovated several times since then.

The monastery is dedicated to Saint Nicholas and includes a central church, several chapels, a library, and a museum. The church is decorated with impressive frescoes and icons and contains the relics of several saints. The library of the monastery contains a collection of more than 5,000 manuscripts, including rare and valuable works from the Byzantine era. The museum houses a collection of ecclesiastical objects, vestments, and manuscripts.

Gregoriou Monastery is known for its beautiful gardens, which include a variety of flowers, herbs, and fruit trees. The monastery also has an olive grove and produces its own olive oil, which is renowned for its high quality. The monks of the monastery are also involved in beekeeping, wine making, and fishing.

The monastery is open to visitors, although access is restricted to men only, in accordance with the rules of Mount Athos. Visitors can tour the central church, the library, and the museum, and can stay overnight in the guesthouse. The monastery is a popular destination for pilgrims and tourists interested in Eastern Orthodox culture and history.