The cathedral gives access to the archaeological remains in the crypt of the neighbouring original palaeochristian church of
Santa Restituta where there is a Greek wall belonging to the temple of Apollo, in
opus reticulatum. Under the apse the peristyle of a late imperial
domus can be seen; also a stretch of Roman aqueduct after the foundation of the city and a stretch of Greek road on an inclined plane. Another attraction of the interior is the
Royal Chapel of the Treasure of San Gennaro, with
frescoes by
Domenichino and
Giovanni Lanfranco, altarpieces by Domenichino,
Massimo Stanzione and
Jusepe Ribera, the rich high altar by
Francesco Solimena, the bronze railing by
Cosimo Fanzago and other artworks, including a reliquary by French masters of the 14th century. Other artworks include an
Assumption by
Pietro Perugino, canvasses by
Luca Giordano and the palaeo-Christian baptistery, with mosaics from the 4th century. The main chapel is a restoration of the 18th century, with a Baroque relief by
Pietro Bracci. The Minutolo Chapel, mentioned in
Boccaccio's
Decameron, has 14th-century frescoes. The
crypt is by the Lombard
Tommaso Malvito. The façade was reworked by
Enrico Alvino in the late 19th century, but retains the 15th century portal, including some sculptures by
Tino da Camaino. File:Naples Cathedral - Duomo di Napoli, Central nave (5325).jpg|View of the interior, towards the apse File:San Gennaro's chapel - Dome (Naples).jpg|Dome of the Royal Chapel of the Treasure of St. Januarius File:Naples Cathedral - Duomo di Napoli, Apse, detail (5334).jpg|Detail of the apse ==Miracle of the Blood==