Inside the cathedral, between the first and second pillars on the right of the central nave, a stairway descends to the site of the ancient basilica of Santa Reparata, brought to light during an archaeological campaign lasting from 1965 to 1973.
Here, the visitor experiences a journey back in time, through the construction phases of one of the first Christian temples in the history of Florence. The ancient basilica remained standing and was officiated for more than eight centuries, from its founding early in the fifth century to its demolition in 1379, year of completion of the basilica body of the new cathedral of Santa Maria del Fiore. The new church was in fact much larger, and until demolition had contained the old building in the manner of a nesting box. The underground site is dominated by the remains of the early Christian building, itself one of the largest early-medieval churches of the Tuscia region: 50 metres (164 feet) in length and 25 metres (82 feet) wide, in triple-nave basilica plan, adorned with an extraordinary mosaic floor in geometric motifs, with Solomonic knots, vases and the figure of a grand peacock (symbol of eternity and resurrection), flanked by a tablet bearing the names of the financing benefactors.
The site also includes remains from the still earlier Florence of Roman times, and traces of Carolingian renovations to the basilica - involving the addition of two side chapels in the apse area, a small crypt and a new stone floor - and finally the remains of the Romanesque transformations of 1050-1106, when a raised choir and new crypt were built. Visitors will also find an extraordinary series of burials from various periods, with many funerary tombstones of the 14th century from the ancient basilica and an ancient cemetery area. Among these, In the centre, stands the tomb of the Gonfalonier (High Magistrate) Giovanni de Medici and his funeral equipment- consisting of a sword, chainmail and gilded spurs - kept in two display cases, together with other artefacts from various sepulchres, including finely crafted buckles and two pallias robes, probably belonging to popes Nicholas II and Stephen IX, regnant in the years 1057-1061. The remains of the mural decoration with Christ in pity in the right apse, datable to the last years of the building's life, are astonishing.
In the entrance area of the bookshop, through a grate, visitors can admire the tomb of Filippo Brunelleschi, marked by a simple stone with epitaph.
Access is from the Cathedral “Porta Campanile” (south side, beside the Bell Tower entrance). Visitors arrive at Santa Reparata by going down a short staircase in the second bay of the right aisle of the Cathedral (no lifts).