a crusade for the Holy Land, pushed for a union with the Eastern church, and did what he could to maintain peace between the Christian nations. He also launched a mission to convert the Tatars, but he died before it could start. To secure the necessary quiet for his medical studies, he had an apartment added to the papal palace at Viterbo, to which he could retire when he wished to work undisturbed. On 14 May 1277, while the pope was alone in this apartment, the ceiling collapsed; John was rescued alive from beneath the rubble; however, he died of his serious injuries on 20 May, possibly an early recorded case of crush syndrome. He was buried in the Duomo di Viterbo, where his tomb can still be seen. The original porphyry sarcophagus was destroyed during the cathedral's 16th-century refurbishment, and was replaced with a more modest one in stone with the pope's effigy. In the 19th century, the Duke of Saldanha, as Portuguese Ambassador to the Holy See, had the pope's remains transferred to a new sarcophagus sculpted by Filippo Gnaccarini. In 2000, the Lisbon City Council, led by Mayor João Soares, successfully had a new funeral monument built in lioz stone, topped by the original stone effigy of the pope, placed in a more condign location in the transept. Legacy After his death, it was rumored that John XXI had actually been a necromancer (see also Communion of the Saints), a suspicion frequently directed towards the few scholars among medieval popes (see, e.g., Sylvester II). It was also said that his death had been an act of God, stopping him from completing a heretical treatise. Since the works of "Peter of Spain" continued to be studied and appreciated, however, Dante Alighieri placed "Pietro Spano" in his Paradiso's Sphere of the Sun with the spirits of other great religious scholars. See also List of popes References Bibliography Guiraud, J. and L. Cadier (editors), Les registres de Grégoire X et de Jean XXI (1271-1277) (Paris, 1892–1898) [Bibliothèque de l'Ecole française à Rome, série 2, 12] (in Latin) Walter, Fritz, Die Politik der Kurie unter Gregor X (Berlin, 1894) (in German) Stapper, Richard, Papst Johannes XXI. Eine Monographie (Münster 1898) [Kirchengeschichtliche Studien, volume 4, no. 4] (in German) Gregorovius, Ferdinand, History of Rome in the Middle Ages, volume V, part 2, second edition, revised (London: George Bell, 1906) H. D. Sedgwick,