The Pedrera Bridge over the Alberche River was built in the 18th century by Marcos de Vierna, Director of Roads and Bridges of the Kingdom during the reign of King Charles III. Despite being built during the Enlightenment, it is an example of a bridge designed based on the traditional knowledge of master stonemasons, a position contrary to the current trend favouring scientific advances and the application of new calculations and construction theories.

Like any historic bridge, the Pedrera Bridge underwent several interventions and rehabilitations, with the most notable event being the destruction of five of its spans during the Spanish Civil War. However, the structure withstood these and other challenges for 250 years until the extreme weather event “DANA” in early September 2023, when the significant flooding of the Alberche River blocked its arches and demolished part of its piers and deck. Ten spans of the existing Pedrera Bridge collapsed, leading to the construction of a new bridge, less vulnerable to the river, while preserving the ruins of the 18th-century bridge due to its historical importance.

The first bridge, built in 1761, “was erected by the neighbouring town of Villa del Prado to facilitate the passage of goods carts to Madrid and El Escorial, as the frequent floods of the Alberche River hindered communication with these municipalities”. The project was commissioned to the architect Marcos de Vierna, executed by master builders Antonio de los Cuetos and José de Isla, and completed in 1765. This bridge had stone piers and a wooden deck.

The wooden deck was replaced in 1844 due to its deterioration. The bridge was then composed of 26 spans of segmental arches made of brick masonry, resting on granite ashlar piers with pointed cutwaters (7.20 m span between the axes of the piers), following the typical design of 18th-century bridges. The ashlar piers were of large dimensions (2 feet thick), and the cutwaters had granite caps. The three-centered segmental arches and vaults (2.5 feet thick) were made of brick laid in a herringbone pattern and bonded with hydraulic lime mortar. In 1850, the bridge was modified to add a house for the toll collector, a practice that remained in place until the early 20th century. The house was later demolished to make way for the main road.

In 1981-1984, a deck widening project was carried out by Fernández Ordoñez, Alfredo Granados, and Julio Martínez Calzón, which noted that remnants of the original upper platform remained at the base of the right-bank abutment. From these remains, it could be deduced that the parapets were made of brick, aligned with the spandrel, and rested on a granite cornice, crowned with a rectangular capstone and a triangular upper finish. These parapets were likely demolished and replaced with a reinforced concrete slab extending 0.80 m beyond the spandrels (6.15 m platform width: 5 m for the roadway and two sidewalks/railings of 0.58 m), with whitewashed reinforced concrete railings.

The museumization works included the following activities:

• Consolidation of the remaining structure through cleaning, repointing, riprapping, and other measures aimed at strengthening the masonry.
• Removal of the 1981 interventions to restore the appearance of the bridge to its 18th and 19th-century state.
• Removal and dismantling of Section B, severely damaged by the flooding in 2023.
• Construction of a lightweight metal walkway over the missing spans, ensuring that the historic bridge is accessible and visitable from both riverbanks.
• Landscaping and enhancement of the two abutments, with rest areas and shaded spaces.