Tash Rabat is a carefully restored stone building that was once a caravanserai (an inn) on the Great Silk Road and is, according to one travel writer, one of the best preserved Silk Road sites to be found. "No other retains as much of its original atmosphere".
Maybe one of the reasons it has retained its character is that it is near the main road from Bishkek and Naryn to Torugart, but is set some 15 km up a beautiful side valley in the foothills of the Tien Shan. For many years the turn-off was not sign-posted, so travellers simply passed by unaware of what they were missing.
Leaving the asphalt road between Naryn and Torugart (and Kashgar), vehicles have to take a gravel road crossing a ford of the Kara Suu River and then along the valley of the Tash Rabat river. The slopes are covered with a tussocky grass that gives the impression of corduroy and you see herds of horses and yaks, flocks of sheep and goats - and even the occasional camel grazing on the hillsides.
The exact date of origin is unknown but there is archaeological evidence to suggest that the site was occupied in the 10th century. There is evidence that it was a place of both rest and worship and would have served to protect caravans to and from China from the ravages of the weather and bandits alike, well before the time of either Tamerlane or Genghis Khan.
The Russian explorer Valihanov provided the first description of Tash Rabat to reach the West in 1859. One early report suggests that it was linked to the frontier of the ancient settlement of Osh; another that it was built over 500 years ago for 'charitable purposes'; a third compares it to a cloister; a fourth to a mosque and another links it to the conquest of the Ferghana valley by the Kyrgyz leader, Ulug Bek, who used it as a temporary garrison for some of his troops. Renovations were carried out in the 1980s but are so unobtrusive that it is hard to detect the work.

A centrally domed space is surrounded by some 30 (perhaps 31 - some walls are no longer standing) smaller domed rooms, including a kitchen. Across the large open central space from the entrance is the 'Khan's seat'. Behind this to the right is a small room where two holes in the ground (one 10m deep, the other filled in) served as dungeons. It is possible to wander through the warren of small rooms that would have housed guests. There are stories of a 100m tunnel leading under the hillside from the building to a lookout post on the other side of the hill.
The main road to Torugart trails around the end of the At-Bashi Mountain range via the Ak-Beyit pass but there is a track over the hills via the Tash-Rabat pass (3968 m) to Lake Chatyr Kul (just 8 km away) and views of the Chinese border. The trek takes about 4 hours (one way). Horse riding can also be arranged.
It is possible to camp in the valley and there are yurts set up in the immediate neighbourhood.