The Torre Toblino was used as a military observation post by the Austrians during WWI. There were two routes built on the tower, and both are now interesting via ferrata. The steeper and harder route is the Via Ferrata delle Scalette, and the other easier route is the Sentiero Curato Militare Hosp. Both are usually climbed in a single outing, usually with an ascent of the VF Scalette, and a descent of the Sentiero Hosp. If one prefers the easiest way to climb the Torre Toblino, then an ascent and descent of the Sentiero Hosp is in order.
The Torre is a steep-sided tower of rock not far from the rifugio Locatelli, and this route description is based on an outing that leaves from that rifugio (the rifugio Locatelli is easily reached on a wide path from the end of the road at the Rifugio Auronzo, a hike of about 4.5 km or so and that takes perhaps an hour and half or two).
Starting off from the rifugio, take path 105 north west below the Sasso di Sesto, a lower rock structure closer to the rifugio. The path leads generally north, eventually climbing up to shoulder on the north-west ridge of the Torre Toblino. There are excellent views back to the Tre Cime from along this trail.
At this shoulder, there are several wartime trenches and ruins scattered about.
Climbing old Fortifications
You now climb up the crest of the should to the north-west base of the tower. The base of the tower here is honeycombed with all sorts of wartime tunnels and windows. If you are interested in a little spelunking before starting your climb....
A path continues along the northern base of the tower, in a clockwise direction, eventually reaching the start point of the Via Ferrata delle Scalette. A big red arrow leads up to the commemorative plaque and the start of the wires, which lead straight up.
Although the climbing is steep, it is usually in some sort of shallow gully with excellent handholds. A little higher up come the first of a series of many ladders. Although airy in spots, the ladders are quite secure and well-protected, with the only real difficulty being that some ladders are a bit overhanging, making them a bit strenuous.