In the heart of the Sierra de Francia mountain range, within the Las Batuecas Natural Park, lies the unique village of Monsagro. This settlement in the province of Salamanca, Castile and León, attracts travelers with its extraordinary history: hundreds of millions of years ago, this place was an ocean, and today its traces are literally embedded in the stones that make up the local houses.
A walk through the streets of Monsagro is a journey back in time, 450 million years ago, to the Ordovician period. The local quartzite slates, used for centuries as building material, contain remarkably well-preserved marine fossils. On building facades, within the stonework, and even on the cobblestones, you can easily spot traces of trilobites—extinct marine arthropods—as well as fossilized evidence of ancient worms and other prehistoric organisms.
Thanks to this geological heritage, Monsagro has become an open-air museum. The local authorities have developed a special route, the “Ruta de las Huellas Fósiles” (Fossil Footprints Route), which runs along the main streets of the village. Information panels help visitors identify different types of fossils, while augmented reality technology offers a vivid glimpse of what these ancient sea creatures looked like in their natural environment.
For those interested in exploring the region’s paleontological history in greater depth, the Interpretation Center “Museum of Ancient Seas” (Museo de los Mares Antiguos) has opened in the village. Through multimedia projections and virtual reconstructions, the museum’s exhibits transport visitors to the bottom of a vanished ocean. Additionally, Monsagro is home to an Ethnographic Museum, which displays household items and tools illustrating the traditional way of life in this mountainous area.
Monsagro attracts visitors not only with its unique geology but also with its picturesque surroundings. The village is situated on the banks of the río Agadón, where natural swimming spots are arranged for summer, such as the Charco de los Mozos pool. Several hiking trails start here, winding through oak and chestnut groves. Nearby lies one of the region’s main attractions—Peña de Francia, whose summit features a Dominican monastery and offers breathtaking panoramic views.
