The Monastery of San Xulián de Samos (Galician: Mosteiro de San Xulián de Samos; Spanish: Monasterio de San Julián de Samos) is an active Benedictine monastery in Samos, Galicia, Spain. It was founded in the sixth century.

The monastery was the School of Theology and Philosophy. It is also an important stop on the Way of Saint James, a pilgrimage leading to the shrine of the apostle Saint James the Great.

The foundation is attributed to Martin of Braga. It is known to have been renovated by Saint Fructuoso in the seventh century. However, the first written mention of this event is from the year 665. An inscription on the walls of the cloister of the lodge says that the Bishop of Lugo Ermefredo rebuilt it. After this restoration it was abandoned before the Muslim invasion until the reconquest of King Fruela I of Asturias, which took place around 760. When, years later, he was assassinated, his widow and son, the future Alfonso II of Asturias, the Chaste, found refuge in the monastery. That earned the monastery royal protection, starting with the properties in a half-mile radius, which would encourage growth.

In the early tenth century, the bishop of Lugo, Don Ero, attempted to seize control and expelled the monks. The Counts Arias Menéndez and Gutierre Menéndez, children of Hermenegildo Menéndez, were required to repopulate the new monastery with monks. Thereafter there were good relations between the monastery and the Count's family.

In the same century it was reoccupied at the behest of King Ordoño II of León. From 960 the community lived under the rule of St. Benedict, but in the twelfth century the Cluniac reform joined with Bishop Don Juan. The monastery of Samos enjoyed great importance during the Middle Ages, which is reflected by its two hundred villas and five hundred sites. In 1558, already incorporated into the Royal San Benito of Valladolid, the monastery suffered a fire that forced its complete rebuilding. The community was dispossessed in 1836, with the confiscation of Mendizabal, but the Benedictine monks returned in 1880.

It suffered another fire in 1951, after which it had to be rebuilt again.

Recent multidisciplinary research has revealed significant insights into the landscape transformation around Samos Abbey over the past 1200 years, highlighting the pivotal role of monastic activities in shaping the surrounding agrarian spaces. This comprehensive study, employing archaeological surveys, palynology (pollen analysis), geochemical analysis, and both OSL (Optically Stimulated Luminescence) and radiocarbon dating, has unveiled at least four main phases of landscape transformation in the vicinity of the abbey.

Key findings include:

• Iron Age Terracing: Evidence suggests that the area around Samos Abbey was terraced as early as the Iron Age (364–150 BC), indicating a long history of agrarian use and modification of the landscape preceding the establishment of the monastery.
• Early Medieval Period: OSL dating indicates the creation of agricultural terraces around the eighth and ninth centuries AD, coinciding with a pivotal period of refoundation and expansion of the monastery. This period saw the establishment of the monastery as a significant power center, protected by the kings of Asturias-León, and suggests that the creation of these terraces may have been part of broader agricultural intensification initiatives.
• Thirteenth Century Development: The construction of new terraces in the thirteenth century aligns with a phase of significant architectural development at the abbey, including the construction of the new Romanesque church. This phase likely reflects intensified exploitation of the surrounding lands to support the monastery's growth.
• Seventeenth Century Transformation: The most extensive and visible transformation occurred in the mid-seventeenth century, involving the reconfiguration of existing terraces and the creation of new agrarian spaces. This period of landscape modification was part of wider changes within the monastery’s lands, potentially driven by economic and social factors.

The study highlights the monastery's role not just as a religious and cultural institution but as a key agent in the transformation and management of its surrounding landscape, reflecting broader trends in monastic land use across Europe. The integration of archaeological, palynological, and dating techniques has provided a nuanced understanding of the dynamic relationship between the monastery and its agrarian environs over the centuries.

There are several architectural styles: late Gothic, Renaissance and Baroque.

• Way of Saint James

• Abbey website

42°43′55″N 7°19′34″W / 42.73194°N 7.32611°W / 42.73194; -7.32611