The first section of this beautiful trail allows you to reach the Carceri Hermitage on foot, without using the tarmac road, as in summer the road is sun-baked, with a lot of traffic. The trail up to Croce di Sassopiano is rather steep, and thus challenging, but it also offers unforgettable views; the most skilled and demanding hikers can easily add a walk uphill to the top of the mountain. The trail starts in Assisi, next to Rocchicciola, or Rocca Minore – the Smaller Fortress – a medieval building which is worth a visit. It was most likely built in 1353-1357 A.D., on commission of the Cardinal Albornoz, although a document written in Vulgar Perugian dates it back to 1200 A.D. From the tower, which is provided with a shady picnic area, take trail 50 and follow the uphill unsurfaced road for about 2 km, until you reach San Rufino Spring; then the trail joins a tarmac road leading to the Carceri Hermitage. This is one of the most cherished spiritual destinations of the Park; originally, it was a small chapel surrounded by the grottos where hermits used to dwell and meditate; afterwards, St Francis named the place "Carceri" – "Jails" – as a synonym of retreat and seclusion. The early structure was extended in 1400 A.D., thanks to St Bernardine of Siena, who built a monastery and the small church of Santa Maria delle Carceri. The Hermitage is shrouded in a lush holm-oak thicket, where you can still find the age-old, legendary holm oak, the so-called "Birds' tree", where, as the legend says, birds used to alight to sing for the saint and to receive his blessings. From here, take the trail 60, first on a road, then, on the left, on an uphill path leading to Croce di Sasso Piano, where you can enjoy a charming view over the valley and the city of Assisi. Trail 50 will subsequently lead you, through the meadow on top of Mount Subasio, to the Vallonica refuge, and then, downhill, back to the Carceri Hermitage, from where you can get back to the starting point. Speleologists and potholing fans can visit Subasio's Grotto, whose entrance is marked on the map – in Sasso Piano area –, as well as Vallonica and Rimboschimento potholes.