the altar of the Navicella, the right transept with altars of Saint Erasmus, Saints Processo and Martiniano, and Saint Wenceslas, the altar of St. Jerome, the altar of Saint Basil, the Gregorian Chapel with the altar of the Madonna of Succour, the larger Chapel of the Holy Sacrament, the Chapel of Saint Sebastian and the Chapel of the Pietà. The Monuments, in a clockwise direction, are to: Maria Clementina Sobieski, The Stuarts, Benedict XV, John XXIII, St. Pius X, Innocent VIII, Leo XI, Innocent XI, Pius VII, Pius VIII, Alexander VII, Alexander VIII, Paul III, Urban VIII, Clement X, Clement XIII, Benedict XIV, St Peter (Bronze Statue), Gregory XVI, Gregory XIV, Gregory XIII, Matilda of Canossa, Innocent XII, Pius XII, Pius XI, Christina of Sweden, Leo XII. At the heart of the basilica, beneath the high altar, is the Confessio or Chapel of the Confession, in reference to the confession of faith by St. Peter, which led to his martyrdom. Two curving marble staircases lead to this underground chapel at the level of the Constantinian church and immediately above the purported burial place of Saint Peter. The entire interior of St. Peter's is lavishly decorated with marble, reliefs, architectural sculpture and gilding. The basilica contains a large number of tombs of popes and other notable people, many of which are considered outstanding artworks. There are also a number of sculptures in niches and chapels, including Michelangelo's Pietà. The central feature is a baldachin, or canopy over the Papal Altar, designed by Gian Lorenzo Bernini. The apse culminates in a sculptural ensemble, also by Bernini, and containing the symbolic Chair of Saint Peter. One observer wrote: "St Peter's Basilica is the reason why Rome is still the centre of the civilized world. For religious, historical, and architectural reasons it by itself justifies a journey to Rome, and its interior offers a palimpsest of artistic styles at their best ..." The American philosopher Ralph Waldo Emerson described St. Peter's as "an ornament of the earth ... the sublime of the beautiful." Status St. Peter's Basilica is one of the papal basilicas (previously styled "patriarchal basilicas") and one of the four Major Basilicas of Rome, the other Major Basilicas (all of which are also Papal Basilicas) being the Basilicas of St. John Lateran, St. Mary Major, and St. Paul outside the Walls. The rank of major basilica confers on St. Peter's Basilica precedence