The Museum of Sacred Art contains some very valuable pieces that are part of the treasure of the Monastery of Santa Cruz. Highlights include the chasuble that belonged to the Martyrs of Morocco, in fabric of Moorish origin, dating from the 13th century, and some vestments, from the 18th century, embroidered with gold thread, as well as some liturgical implements.

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In the so-called Treasure Chapel, there is a Silver Reliquary Bust (dating from 1610) containing the skull of St. Theotonius (visible through the crystal on the "chest"), one of the founders of the Monastery and its first prior and first Portuguese Saint (he was canonised in 1163, a year after his death).

 

This reliquary is flanked by two smaller reliquary busts, also in silver (dating from 1510) with the relics of the Martyrs of Morocco.