The Plaza Mayor was built during Philip III's reign (1598–1621) and is a central plaza in the city of Madrid. It is rectangular in shape, measuring 129 m × 94 m and is surrounded by three-story residential buildings having 237 balconies facing the Plaza. It has a total of nine entrance ways.
The origins of the Plaza go back to 1577 when Philip II asked Juan de Herrera, a renowned Classical architect, to discuss a plan to remodel the busy and chaotic area of the old Plaza del Arrabal. Juan de Herrera was the artist who designed the first project in 1560 to remodel the old Plaza del Arrabal but construction did not start until 1617, during Philip III's reign. The king asked Juan Gómez de Mora to continue with the project, and he finished the porticoes in 1619. Nevertheless, the Plaza Mayor as we know it today is the work of the architect Juan de Villanueva who was given the glorious, albeit difficult task of its reconstruction in 1790 after a series of enormous fires. Giambologna's equestrian statue of Philip III dates to 1616, but it was not placed in the centre of the square until 1848.
The Plaza Mayor has been the scene of multitudinous events, during the Spanish Inquisition were practicated the autos de fe against supposed heretics and the executions of those condemned to death.
There is a bronze statue of King Philip III at the center of the square, created in 1616 by Jean Boulogne and Pietro Tacca.
The city walls of Avila were built in the 11th century to protect the citizens from the Moors. They have been well maintained throughout the centuries and are now a major tourist attraction as well as a UNESCO World Heritage Site. Visitors can walk around about half of the length of the walls.
The layout of the city is an even quadrilateral with a perimeter of 2,516 m. Its walls, which consist in part of stones already used in earlier constructions, have an average thickness of 3 m. Access to the city is afforded by nine gates of different periods; twin 20 m high towers, linked by a semi-circular arch, flank the oldest ones, Puerta de San Vicente and Puerta del Alcázar.