Bonilla de la Sierra

Long before the medieval bishops arrived, people were leaving their mark on the hills around Bonilla. Researchers from the Ávila Cultural Heritage Service found two rock altars at a site called Navalterrero, dated somewhere between 5000 and 1000 BC — spanning the late Neolithic to the Bronze Age. Both are granite sanctuaries with steps cut into the rock leading to the top, similar in form to the altar at the Castro de Ulaca. A third rock altar, the Canto del Mortero, had already been identified nearby, dating to the late Bronze Age.

The town's recorded history begins with the Bishop of Ávila, whose diocese had held Bonilla since at least 1224. Between 1312 and 1348, Bishop Sancho Blázquez Dávila fortified it, raising the castle and walls that still define the townscape today.

The castle's most dramatic moment came in 1440, when King Juan II of Castile used it as a refuge from February to late April while political tensions with the Infantes of Aragón threatened the Crown. Bishop Lope de Barrientos was lord of Bonilla at the time. Later, the castle sheltered the future king Enrique, Prince of Asturias, in 1448 and again in 1451.

Among the bishops who passed through Bonilla, Alonso de Madrigal — known as El Tostado — stands out. Considered the most learned theologian of his era and a forerunner of Spanish humanism, he died in Bonilla on 3 September 1455. He is buried in Ávila Cathedral, where his tomb, carved by sculptor Vasco de la Zarza, can still be seen.

Other notable figures connected to the castle include Fray Hernando de Talavera, confessor to Queen Isabella the Catholic, and bishops Alonso de Fonseca and Alonso Carrillo de Albornoz. The castle remained episcopal property until the 19th-century Mendizábal confiscations removed it from church hands.

Bonilla was declared a protected historic-artistic ensemble in May 1983, a status that reflects the concentration of medieval fabric still standing within its walls.

The castle is now in private hands and largely ruinous, but its exterior is open to visitors. The main tower, fitted with machicolations, has been restored. Inside, some rooms still show traces of polychrome frescoes depicting tournament scenes and battles between men and fantastical animals. The walls originally had four gateways: the Puerta de la Villa (or Puerta de Piedrahíta) to the south, bearing the coat of arms of Bishop Blasco Jimeno; the Puerta del Mirón to the west; the Puerta de Ávila to the north; and the Postigo de Villafranca to the east. In 2016, the Ávila Provincial Council and the local council carried out the first archaeological excavations and consolidation work on the southern wall.

In the town stands a large monumental stone cross on a stepped base, its rounded arms carved with a figure of Christ, with heraldic shields decorating the rectangular block beneath.

The main monument is the Collegiate Church of San Martín de Tours, declared a monument of national heritage interest (BIC) in 1931. Construction began in the early Gothic style — apse and nave first — with pure Gothic windows added as work progressed. Buttresses were added when the apse showed signs of stress, and the large windows were opened in 1430. The bell tower was completed around 1513. The original high altarpiece dedicated to San Martín, made in 1514, no longer exists, but its painted panels were incorporated into the current Baroque retable, built around 1701 and attributed to Manuel González Delgado. The side altarpieces and the Cristo Yacente retable date from between 1720 and 1740. The Renaissance chapel of the Guzmanes family, dated to the early 16th century, was later expanded with pilasters and a trilobed attic. Local tradition holds that the church's staircase has as many steps as there are words in the Creed.