According to legend, a wealthy Roman had a dream on 4 August 352 in which he was directed by the Blessed Virgin Mary to construct a basilica on a site which she would reveal to him. The following night, a snowfall took place on the Esquiline Hill, a truly miraculous event as anyone who has experienced a Roman August would know, and Pope Liberius (r. 352-356) initiated the construction of the first basilica, which stood in a location about one block in front of the present one. (here's a video I took in August of it "snowing" inside the basilica - to commemorate the miraculous event)
Although it is unclear if this first basilica was dedicated to the Blessed Virgin from its foundation, the definition of our Lady as the Mother of God at the Council of Ephesus in 431 brought about a new flowering of devotion to her. In this atmosphere, Sixtus III began to build a new basilica to her honor in a slightly different location. It is this building that, while much modified, comes down to us today. The basilica began to be known as St. Mary Major, as the principal church in Rome dedicated to our Lady, in the seventh century, the same period in which the relics believed to be from the manger of Christ at Bethlehem were enshrined here. Various minor changes took place over the next few centuries. One of the more interesting of these concerns the decision of St. Paschal I in the early ninth century to raise the episcopal throne in the apse because, on account of its nearness to the women’s area in the church, his private conversations could be overheard by them. Later in that century a more serious event transpired when Adrian II approved Ss. Cyril and Methodius’ translation of the liturgy into Slavonic in this church.
The medieval period saw several changes here. In 1291, a new chapel was created for the relics of the manger, known as the Chapel ad Praesepe.
Four years later, the rear wall and apse were demolished and a transept and new apse were built. At the same time the new apse and the façade of the basilica were decorated with mosaics in the style of the day. The late fourteenth century saw the addition of the campanile (bell tower), the tallest in Rome, with the following century seeing the construction of several small chapels off of the aisles. Pope Alexander VI, archpriest of the basilica before his election to the papacy, installed a new ceiling at the end of the fifteenth century. St. Charles Borromeo was archpriest here from 1564 to 1572 and undertook some renovations in the choir. In 1587, the Chapel of the Blessed Sacrament, also known as the Sistine Chapel because of its patron, Sixtus V, was completed. Into it was also put the Praesepe Chapel, set into the floor beneath the altar. On the other side of the basilica the Lady Chapel was completed in 1611 under Pope Paul V of the Borghese family, whose name is also found on the façade of St. Peter’s. In 1673 the exterior of the apse was decorated in the Baroque style, with the other exterior surfaces of the basilica receiving a similar treatment under Pope Benedict XIV about seventy years later. Thankfully, these preserved much of the mosaic work on the façade. The confessio before the high altar was built between 1861 and 1864 to house the relics of the manger. Despite this long history of renovations and renewals, the interior of the basilica still preserves its original spirit.
Standing in the square before the basilica today, a couple of things draw our interest before we enter the church itself. The first of these is the Marian Column in the center of the square. The column is originally from the Basilica of Maxentius in the Roman Forum. This is the inspiration for the many Marian columns which can be found in various cities throughout Europe. The second point of interest here are the mosaics on the old façade of the basilica, currently protected behind the columns of the eighteenth century loggia. They depict Christ attended by angels, in the heavenly liturgy, and scenes from the legend of the basilica’s foundation. These mosaics served as the apse for liturgies celebrated in the piazza.