The Sanctuary is a Reliquary Chapel with an elliptical structure inside, clearly Baroque with Rococo decoration, built to bring together in one space all the relics that were scattered throughout the monastery. The date of its construction is uncertain, but it was certainly during the 18th century. Of its structure, highlights include the windows, the yellow, red and green glass chandelier (18th century), which complements the natural light and accentuates the brightness of the composition, the floor (with high “illusionist” potential for creating optical illusion) and the main altarpiece.

This Sanctuary contains relics from various eras, integrating the most dear figures of the Crosier ideology: popes, bishops, apostles, martyrs and various saints.

Of the many relics found here, we highlight those of the Martyrs of Morocco (who arrived at the Monastery in 1220) and Saint Teotónio (first Prior of the Monastery and first Portuguese Saint) which are found inside the small reliquary chests decorated with gilded carvings and placed , roughly in the middle of the chapel, on the left and right sides, respectively.
All the pieces found in this Sanctuary are reliquaries, including 12 pyramids with 4 faces, which represent the 12 months of the year and the 4 weeks of each month. In these pyramids, relics were placed taking into account the month and week of the death of the saint whose relics they contain.

This space will probably be one of the most striking and highly symbolic religious spaces in the Monastery of Santa Cruz, even though all the spaces in this monastery are loaded with religious symbolism.