The basilica of Santa Maria Maggiore (Saint Mary Major) is the most important of the Roman churches dedicated to the Madonna. 

It rises on top of the Cispio (the highest of the three ramifications that make the Esquiline Hill) on the ruins of a complex founded in the Augustan age and successively enlarged and decorated with frescoes. 

The original church – with three naves, without a transept and with a narthex – was founded between 432 and 440 by Sixtus the Third after the Council of Ephesus in 431 had sanctioned the dogma of Mary’s divine maternity.

The tradition that the church was founded by pope Liberius on the spot of a miraculous snowfall that occurred on August 5 356 – hence the names of Basilica Liberiana and Santa Maria ad Nives used in the past – must be considered a legend. Between 1145 and 1153 Eugene the Third rebuilt the narthex, reducing it to a portico, and put in place the Cosmati floor. 

Under the papacy of Nicholas the Fourth (1288-1292) a new apse was built and moved back in order to create the transept decorated with paintings. 

The mosaic decoration of the new dome was commissioned to Jacopo Torriti. The construction of the bell-tower dates back to the second half of the fourteenth century and was completed later by cardinal Eugene d’Estouteville, archpriest of the basilica from 1445 to 1484, who also covered the side naves with vaults and built the chapel of San Michele. At the end of the fifteenth century pope Alexander the Sixth Borgia covered the ceiling of the central nave with the current lacunar. 

Deep transformations of the basilica that had until then conserved its substantially medieval appearance were started between the end of the sixteenth and the beginning of the seventeenth century by Sixtus the Fifth and Paul the Fifth, who built the two great side chapels, called Sistine and Pauline after them, and the building on the right of the facade. Between 1670 and 1676 Carlo Rainaldi redesigned the apse in its current forms. 

The last great interventions that gave the basilica its current appearance are due to the fancy of Ferdinando Fuga, Florentine architect that in the first half of the eighteenth century completed the palace on the left of the facade and reconstructed the facade creating one the finest examples of the so-called Roman late baroque. 

The eighteenth century facade is placed upon the more ancient one, conserving the original mosaic decoration, inserted in the Loggia delle Benedizioni accessible from a staircase under the arcade. 

The mosaics are end of the thirteenth century works by Filippo Rosuti and represent in the upper register, Christ benedictive among the symbols of the Evangelists, the Virgin, angels and Saints, while the lower register shows episodes of pope Liberius’s life. 

This basilica is the only patriarchal basilica to still conserve an appearance similar to the original one: an imposing structure with three naves divided by reused ancient columns that terminates in the apse behind a triumphal arch. The mosaic panels dated back to the fifth century are still visible on the walls of the central nave above the trabeation. 

The ceiling is of the time of Alexander the Sixth Borgia (1492-1503) and by tradition was gilded using the first load of American gold donated by Isabel of Spain. The Stories of the Virgin between the large windows date back to the end of the sixteenth century. 

The triumphal arch is decorated with mosaics representing Stories of Christ’s childhood of the period of Sixtus the Third. A beautiful mosaic in the apsidal dome was made and signed by Iacopo Torriti at the end of the thirteenth century. The work represents the Crowning of Mary between the clients Nicholas the Fourth and Giacomo Colonna and Saints. The marble bas-reliefs by Mino del Reame (around 1474) placed below, were already in the ciborium of the papal altar. 

Tondi frescoed with figures of Prophets are visible in the transept and were brought to light in 1931, variously attributed to Cavallini, Cimabue or to young Giotto. The right nave gives access to both the baptistery – designed by Flaminio Ponzio in 1605 and decorated by Passignano - and from the baptistery to the Sacristy on the right, and to the Chapel of San Michele that presents traces of frescoes that might have been works by Piero della Francesca. 

Back to the right nave, there is first the Chapel of Relics and then the huge Sistine Chapel wanted by Sixtus the Fifth Peretti (1585-1590) who commissioned it to Domenico Fontana (1584-1587). 

The chapel was completely frescoed by artists of the late Roman Mannerism directed by Cesare Nebbia and Giovanni Guerra and englobes the ancient Oratory of the Crib that was placed here by Fontana and can be accessed through a stairway. The sculptural decoration of the sacellum (votive chapel) is partly due to Arnolfo di Cambio. On the floor outside the chapel a simple marble slab closes the tomb of the Bernini family, where Gian Lorenzo was also buried. 

Symmetrical with the Sistine Chapel and just as sumptuous, the Pauline Chapel opens on the left nave. It was designed for Paul the Fifth Borghese (1605-1621) by Flaminio Ponzio. In comparison with the Sistine Chapel, the Pauline Chapel presents a higher quality of pictorial decoration that was in part painted by Cavalier d’Arpino and Guido Reni. The sacristy of the chapel can be accessed from the right of the altar. 

The sacristy leads to another chamber, where a Madonna with Child by Beccafumi and a Slope to the Calvary by Antonio Bazzi called the Sodoma are kept. 

Members of the Borghese family are buried in the cellars of the Pauline Chapel, including Pauline Bonapart, sister of Napoleon the First. Proceeding down the left nave there is the spectacular Sforza Chapel with an elliptical plan designed by Michelangelo and built by Tiberio Calcagni and Giacomo della Porta between 1564 and 1573.