The Santa Cruz Monastery, (English: Monastery of the Holy Cross, Portuguese: Mosteiro de Santa Cruz, best known as Igreja (Church) de Santa Cruz is a National Monument in Coimbra, Portugal. Because the first two kings of Portugal are buried in the church it was granted the status of National Pantheon. Founded in 1131 outside the protecting walls of Coimbra, the Santa Cruz Monastery was the most important monastic house during the early days of the Portuguese monarchy. St. Theotonius founded this community of canons regular and served as their first prior. The monastery and church were erected between 1132 and 1223. The monastery was granted numerous papal privileges and royal grants, which allowed the accumulation of considerable wealth, at the same time as it consolidated its position on the politico-institutional and cultural scene. Its school, with its vast library, was highly respected in medieval times and was a meeting point for the intellectual and power elites. Its scriptorium was used for the consolidation of royal power by King Afonso Henriques, thus it was not considered strange that he decided to be buried there.

Nothing remains of the early Romanesque monastery. It is known that it had only one nave and a high tower in the façade, as typical of the Augustinian-Romanesque constructions, but none of those elements subsisted. In the first half of the 16th century, the Monastery was completely renovated by King Manuel's order, this monarch having assumed the Monastery tutelage.