The monastery's treasury houses many important relics. The treasury, along with the monastery's library are temporarily housed over the catholicon's narthex. Among important cultural treasures, such as crosses, books, garments, etc., Esphigmenou has in its possession a large (3.05×2.80 m) part of Napoleon Bonaparte's tent, which was donated to the monastery by Patriarch Gregory V of Constantinople. The monks use this once a year, at the celebration of the Ascension of Christ, as a tent over the entrance of the catholicon.