During the reign of the Catholic Monarchs Isabel and Fernando (1492-1516), a lot of the original decorative work was filled in and whitewashed, and paintings and decorations were destroyed. Emperor Carlos V (1516–1556) then totally rebuilt some parts of the palace in the Renaissance style and added the unfinished Carlos V Palace when he decided to take up residence there. Philip V (1700–1746) then decorated the building in a more Italian style for his palace. During the centuries that followed, the Alhambra fell into a state of disrepair, was inhabited by thieves and beggars and then used as a barracks by Napoleon’s troops. Further damage was caused by the retreating French troops to some of the towers and two of the gates (Puerta de los Siete Suelos and Puerta del Agua) in 1812 and an earthquake in 1821. After centuries of neglect and abandonment, the Alhambra was rediscovered in the 19th century by European scholars and travelers and restoration then began in an attempt to restore it to its former glory. Generally speaking, the square towers were built during the Nasrid dynasty and the round ones during the Christian era.