The church of San Lorenzo, located in the town of Sahagún, province of León, is a parish church in the Mudejar Romanesque style. It is located between the Plaza de San Lorenzo and Calle del Arco, with a longitudinal axis that is oriented from northwest to southwest, so it does not strictly follow the traditional liturgical orientation from west to east.

In 2015, during the expansion of the Way of St. James in Spain approved by Unesco, under the title "Ways to Santiago de Compostela: French Way and Ways of Northern Spain", the church of San Lorenzo was included in the "Retrospective Inventory - Associated Elements" of Spain, appearing at number 1422.

The church of San Lorenzo was built in the first half of the 11th century, mentioned for the first time in a document of 1110, which indicates that in 1092 Count Gonzalo Muñiz built a palace on land behind the church. This temple is an outstanding example of Mudejar architecture with hybrid characteristics that include Romanesque, Gothic and Muslim elements. Unlike the Church of San Tirso, also in Sahagún, San Lorenzo is built entirely of brick.

The interior has a basilica floor plan with three naves separated by pointed arches. At the chevet, the plan is completed with three semicircular apses preceded by straight bays. The lateral naves have wooden roofs, while the central nave has 18th century plaster groin vaults. The apses are covered by quarter sphere vaults, and the space between them and the naves ends in a barrel vault.

On the exterior, the chevet stands out with the triple apse and the impressive tower located over the central section. The central apse is composed of three levels of different heights: the lower level with double horseshoe arches, the middle level with simple horseshoe arches framed in rectangles, and the upper level with a band of blind squares. The west apse has two levels decorated with blind horseshoe arches framed in rectangles and a frieze of angled brick. In the east apse, these elements are irregularly distributed, with a frieze of angled bricks reaching a height of ten bricks.

The tower, a typical example of Romanesque brick architecture, has four levels of square plan that decrease in size with height. The first level features blind windows with horseshoe arches, the second level has bent semicircular windows, and the third level also has pointed windows, surrounded by two lines of impost. The upper level has five smaller windows on each side, also pointed. A circular staircase attached to the north side of the tower, topped with a conical finial in 1983, provides access to the tower.

Next to the church is the Jesus Chapel, where the processional steps used during Holy Week are stored.

In 2011, due to the deterioration of the church and the risk of collapse, Hispania Nostra included it on its red list of endangered heritage. In 2013, major restoration and consolidation work was carried out, including the renovation of many parts, such as the roof.