It's the last town before the border, perched at 4,700m on the Khunjerab Pass. As a result, it's only accessible between May and October - weather permitting!
It was a trading post along the Silk Road, linking China to Pakistan, a place where only the hardiest of travelers would go. The route running from Kashgar to Tashkurgan is worth the effort - it's stunning. Part of it is on the Karakoram Highway, which crosses impressive landscapes and offers breathtaking views before arriving at the Pakistani border.
In Tashkurgan itself, have a stroll around its streets and drop by its little museum. You can also climb up to its stone fortress and take a hike across its surrounding prairies.
Bear in mind that to travel along the Karakoram Highway to Tashkurgan, you'll need a special permit, obtainable via most of Kashgar's travel agencies.