Apennines. Built of stone and masonry exclusively for military purposes and intended only to accommodate troops and never as residence for nobles, the fortress overlooks the Plain of Navelli at one of the highest points in the ancient Barony of Carapelle. Construction of the fortress started in the tenth century as a single watchtower. A walled courtyard with four cylindrical towers at the corners around a taller inner tower was added in the thirteenth century. The lower half of the fortress is built with distinctively larger stones than its upper half. It is believed that this feature was to make its base impenetrable to invaders. The fortress was never tested in battle. However, it was badly damaged in November 1461 by an earthquake with an estimated magnitude of 7 to 8 on the Richter Scale. While the town of Calascio, which lies below the fortress, was rebuilt, the fortress was not. Avezzano Avezzano, having been completely destroyed by the earthquake of 1915, has no monuments of particular interest as do other locations in the region of Abruzzo. However, you can see some important remains of its ancient history. The remains of the ancient Roman site of Alba Fucens are located 7 kilometers north of the city. The Castello Orsini-Colonna was built in 1490 by Gentile Virginio Orsini, who had it built around a pre-existing medieval tower of the twelfth century; it is square, with round towers at the angles. The castle project was probably led by the engineer Francesco di Giorgio Martini. In the sixteenth century the castle was expanded by the order of Marcantonio Colonna, becoming an elegant residence. Severely damaged by the earthquake of 1915, it was partially restored after 1990. The Tunnels of Claudius are located south of the city. They were built by the emperor Claudius between 41 and 52 AD by which the emperor made the first attempts at draining the huge Lake Fucino. To create the tunnels and the main gallery, 25,000 slaves were needed. They dug 32 wells and six tunnels. The lake was largely drained, but with the fall of the Roman Empire the tunnels were obstructed and the lake returned to its previous levels. Many centuries later, Alessandro Torlonia completed the work by finally draining Lake Fucino, building on the original project of the emperor Claudius and turning the land under the great lake into a fertile plain. In 1977, the