The Church of San Ildefonso was constructed in the 11th century on orders of King Fernando I of Leon and Castille. It was remodeled in the 12th, 13th, 15th , and 20th centuries. The design was originally Romanesque. Today there is only one nave. Between 1719 and 1723 Joaquin Benito Churriguera repaired the interior of the church and remodeled the tower. The main altar was created by Manuel Alonso in 1805. The Chapel of La Inmaculada is quite beautiful. The church has the remains of San Ildefonso of Toledo, father of the Latin Church. It also has the remains of San Atilano, the first bishop of Zamora and the patron saint of the city. The remains of Santa Leocadia are also found in this church. The church was declared as a National Monument in 1974.