Xploration date 04/08/2025
Welcome to the exploration of one of Italy’s hidden military masterpieces. Today, we delve into the fascinating history of Forte Serre Marie, a strategic fortress built in the late 19th century to defend the Italian Alps. This article is a continuation of the previously published document Alpine Fortresses.

Perched along the route between Pra Catinat and the Colle delle Finestre, Forte Serre Marie was constructed in 1892 as a defensive outpost for the larger Fenestrelle Fortress, which looms nearby. This secondary fortification, often considered a detached work from Fenestrelle’s extensive complex, was designed to secure the high valley and safeguard the vital road leading to the Valleys’ Fortress.

The fortress itself is a robust rectangular structure, capable of housing around 200 soldiers. Its sturdy stone walls feature rounded edges, built to withstand enemy fire. At the entrance, a grand gateway opens into a fortified compound, surrounded by a deep moat for additional protection. The building’s flat roof was equipped with artillery pieces arranged in a parapet, along with casemates for mortars, ready to repel any assault.

Inside, the fortress reveals a complex network of underground passages and spacious chambers. The vaulted underground rooms housed a massive powder magazine, capable of storing up to 100 tons of explosives—a testament to its formidable defensive purpose. The interior is divided into two levels: the lower for service and storage facilities, and the upper overlooking the courtyard through a series of arches forming a covered gallery.

Throughout the walls, narrow gun slits—called loopholes—are visible, designed for close-range defense. Over the years, the fortress has seen various uses. Between the two World Wars, it served as a storage depot for ammunition and supplies, as well as a shelter for troops.

Today, Forte Serre Marie stands as a silent guardian of Italy’s military history, echoing the strategic ingenuity of past generations. Its battered walls and deserted interiors tell stories of a turbulent era, reminding us of the importance of fortifications in shaping the history of the Alps and Italy as a whole.

Thank you for joining us on this journey into the past. Please find below a video of the exploration of this fortress, and further down, the complete gallery of photos.