Part of the valuable Laurentian complex, the Medici Chapels comprise of the Chapel of the Princes and the New Sacristy, which are the Medici family mausoleum. Started in 1604, the Chapel of the Princes was beautified by the Opificio with semiprecious stones and marble; it was not finished, in any case, as per the first undertaking, which arranged it to be totally fixed with semiprecious stones. In 1826, the frescoes of painter Pietro Benvenuti replaced the eager undertaking for a covering in lapis lazuli. Starting at 1869, the Chapel of the Princes has been an incorporating part of the Museum of the Medici Chapels.