Straight from Lord of the Rings, the ruined ramparts of the Babak fortress loom above a desperately sheer chasm as you edge through a narrow cleft to the final traverse. A trip to the lair of 9th-century Azeri hero Babak Khorramdin should not be missed, as the views of the castle and the surrounding mountains are simply breathtaking. Forget the meagre ruins of the Castles of the Assassins; Babak's the real deal. The ascent will take one to two hours.
Occupying a cultural position somewhere between King Arthur, Robin Hood and Yasser Arafat, Babak is celebrated for harrying the anti-Shiite Abbasid-Arab regime between 815 and 837. There are several access paths to the castle, though the normal route ascends stairs behind the seasonal Babak Hotel. After a short, stiff climb, the stairs end and the views shine as you follow a muddy track, traversing gently to the right before climbing steeply to a hut that sells drinks in summer. Continue sidling right and ascending, and you'll eventually see the stone steps of the cleft. Remember where you join the stone path, as you'll need to return the same way. There are no signs, though the route is fairly obvious. Bring sunscreen in summer and be prepared for icy conditions in winter.
Stronger vehicles can drive up an unsurfaced track to a summer nomad camp, reducing the walk time considerably, though you will pay more for the access. On your return to the road, start walking: something will come by sooner or later.