The Oratory of the Most Holy Crocifisso of the Cave, also called the Oratory of the Grotto of the Cathedral, is located under the Cathedral of Urbino and consists of four chapels erected between the sixteenth and seventeenth centuries. The underground environments of the Duomo were created to bridge the gap between the aphid side of the Cathedral and the slope of the hill. Originally, the first two environments were used as storehouses of the stables of the Ducal Palace while the other two environments were used as the depots of the Cathedral. At the beginning of the sixteenth century, Duke Guidobaldo da Montefeltro handed over the first two rooms of the Underground to the Newborn Brotherhood founded by Father Girolamo Recalchi da Verona, and in 1507 they formed the Society of Humility. During the work to realize the two chapels, a wooden crucifix was found miraculous, from this discovery the brotherhood will be titled to the above Crucifix. The task of the Brotherhood was: the works of charity and the representation of scenes from the Passion, the Old and the New Testament. In 1655 the Brotherhood was joined to the Archconfraternity of the Most Holy Crucifix of Saint Marcello in Rome. He had many privileges and indulgences from the various popes, such as Paul III, Pius IV, Gregory XIII, Clement VIII, Clement XIII, and Urban VIII who in 1636 honored the Company with the privilege of being able to release a condemned to death on Holy Thursday, alternating with the Brotherhood of St. Joseph. This Brotherhood adhered to the most eminent personalities of the city. The Oratory is lit by the so-called Loggia del Grano, decorated in 1621, on the occasion of the wedding between Federico Ubaldo della Rovere and Claudia de 'Medici; once descended 46 steps down a long corridor overlooking the four Chapels and the Giro del Perdono, the Oratory, housed the works from the Treasury of the Basilica of San Marco in Venice to protect them from bombing and from German raids. The Oratory is open to the public and is part of the Albanian Diocesan Museum. This is the first chapel, dominated by the marvelous marble altar of the altar, framing the canvas of the Bolognese painter Emilio Taruffi, depicting the Nativity of Christ, made in 1682. The barrel vault is decorated by a fresco depicting a Glory of Angels of the 'artist Andrea Giannotti, surrounded by a marble frame dating from the eighteenth century. the second chapel was rebuilt, in the early 19th century, in neoclassical forms by the architect Giuseppe Valadier; Inside a niche in the apse is preserved the wooden crucifix dating to the fifteenth century, from which it named the brotherhood. On the vault of the chapel, the symbols of passion are depicted in stucco, while the symbols of the four Evangelists are displayed in the apse. The chapel is lit by five Murano glass chandeliers. In the chapel there is the tomb of the last Duke of Urbino, Federico Ubaldo della Rovere, who died in mysterious circumstances at 18, on June 29, 1623. The third chapel is dominated by the marvelous marble group of Pietà by Giovanni Bandini of the Opera performed in the sixteenth century, perhaps the most important work of the oratory. This work was commissioned by Duke Francesco Maria II to adorn his tomb, but for the premature death of his son Federico Ubaldo. On the altar there is a work by the painter Gian Andrea Urbani, Annunciation of the Virgin of the seventeenth century; while the vaulted vault is decorated by a fresco representing the Triumph of the Cross by Andrea Giannotti. in the 17th century the chapel was moved to the clay terracotta statue, dating back to the fifteenth century, representing the Dead on Christ. The construction of this chapel took place in the 17th century, decorated by a stone finish designed by the architect Ursea Matteo Oddi, brother of the most famous Muzio.