Part of the 13th century expansion of the civic role of the Basilica of St. Mark involved the enlargement of the narthex, which enhanced the space available for ceremonies and processions. Towards the mid-13th century, a north arm was built, laid out as a series of domed bays with semi-circular apses. The tomb of Doge Marino Morosini (Doge from 1249 to 1253), was inserted into the newly created space of the north arm of the narthex as the first monumental ducal tomb erected in the basilica. The entire bay serves as a frame for the tomb. Its placement there, apparently soon after Morosini’s death in 1253, may have stimulated the resumption of work on the narthex mosaics after a gap of approximately two decades. The tomb is made of spolia, Greek and Turkish marble slabs initially used between the 4th and 7th centuries. A work of great historic and artistic importance, it is raised on two blocks of Istrian stone. The urgently needed restoration was extremely delicate and difficult, for the tomb had to be completely dismantled, restored piece by piece, and then reassembled.