Fort Fuentes was a military fort built on the hill of Montecchio or Monteggiolo near Colico in the province of Lecco, in Lombardy, Italy. It was built by the Spanish governor of Milan, Don Pedro Enríquez de Acevedo, Count of Fuentes, to command the Pian di Spagna and the strategic Trivio di Fuentes, the crossroads between the Valtellina, the Valchiavenna and the Alto Lario, in order to defend the northern border of the Spanish domain against the Grisons to the north. Construction was begun in 1603 or October 1609 under military architect Gabrio Brusca, and was substantially complete within three years. Ancillary fortified structures were the tower of Sorico, the Torretta del Passo, the Fortino d'Adda, the Torrino di Borgofrancone, the Torretta di Curcio and the tower of Fontanedo. Like the city of Milan, the fort of Fuentes yielded in 1706 to Prince Eugène of Savoy, ending Spanish control of the area. It is thought that the Samolaco horse derives in part from Spanish stock abandoned by the garrisons of these fortifications.
The fort was visited in 1769 by the Emperor Joseph II, who declared it militarily useless. It was decommissioned in 1782, and the hill auctioned to a private buyer. The fortress was largely demolished in 1796 by general Rambeau on the orders of Napoleon and at the request of the Grisons. During the 19th century the ruins became the refuge of groups of bandits which the Austrian gendarmerie was unable to dislodge. Eight gun emplacements were constructed on the site during the First World War, and the circular Spanish tower on the western side demolished at this time.
In 1987 the entire hill, with the ruins of the fort, was acquired by the province of Como, and later passed to the province of Lecco. The Associazione Forte di Fuentes, an association for the protection of the historic site, was formed in 1998.