Royal Chapel of the Treasure of San Gennaro, Baroque chapel in Naples Cathedral, Italy.

The Royal Chapel of the Treasure of San Gennaro is a baroque chapel inside Naples Cathedral, built from 1608 to designs by Francesco Grimaldi on a Greek cross plan with a central dome. Domenichino and Lanfranco painted the dome frescoes and the figures in the arches and pendentives. Clustered columns, marble panels and side chapels line the nave, and Francesco Solimena's main altar, completed in 1667, frames a silver frontispiece of the Translation of the Relics.

Construction began in 1608 after Naples residents took a vow to build this chapel following a series of calamities that included plagues and volcanic eruptions. The project represented the city's faith and devotion to San Gennaro for protection.

Three times yearly, the chapel displays vials holding the blood of San Gennaro in a ritual that requires both the Archbishop and city officials to open the strongbox together. This event remains deeply meaningful to many local residents.

Audio guides are available in twelve languages including Italian, English, French, German, Spanish, Portuguese, Russian, Ukrainian, Chinese, Japanese, Korean, and Neapolitan. These guides help visitors navigate the chapel and understand its artistic features in their preferred language.

The chapel is not owned by the archdiocese: papal bulls placed it under the city of Naples, represented by the Deputazione and the Sedili. Its construction fund, opened at 10,000 scudi, grew past 480,000 without any contribution from the Church. The gilded bronze screen above the entrance was the work of Giuliano Finelli, trained under Bernini.