According to tradition, Pope Liberius (pope from 352 to 366) and a patrician had the same dream at the same night. The Virgin appeared and expressed her wish to raise a church at the site which she will mark by snow at the middle of the summer. Next day the Esquiline hill was covered by snow and it became the site of the church of Santa Maria Maggiore.The Early Christian church was erected by Pope Sixtus III (432-440) and its mosaic decoration in the nave and the apse also date from this period. The Early Christian apse mosaic has been lost, having been replaced by the one by Jacopo Torriti during a redesign of the entire choir area under Pope Nicholas IV (1288-1292) who commissioned the replacement without entirely changing the original subject matter and retaining the bust of the Saviour, believed to have appeared miraculously at the time of the basilica's consecration. For the expansion of the choir the apse was sacrificed along with its mosaic. The exterior of the new apse is polygonal in form, and is now enclosed in Baroque architecture. Inside, however, it is semicircular.The commission for the new apse mosaic was given to Jacopo Torriti, who left the Lateran workshop around 1291 to assist the work at Santa Maria Maggiore. The main subject of the mosaic is the Coronation of the Virgin, with five scenes from the life of Mary beneath if: the Annunciation, the Nativity, the Adoration of the Kings, the Presentation in the Temple, and the Dormition. The latter, interrupting the chronological sequence of the events, occupies the centre compartment, which places it in a direct relationship to the Coronation in form and content.The subject of the Coronation of the Virgin as linked to her physical resurrection had already been popular north of the Alps as early as the twelfth century. In Italy, however, it found its first inclusion in monumental art in Torriti's mosaic, and it had never before been pictured with such splendour.