You approach Thimphu along a winding, single-lane access road, little wider than the trucks that suddenly emerge around each curve.
With our passage through the bridge, behold a curious transformation.
There is a great variety of people, architecture and scenery in central Bhutan.
The charming small town of Paro lies on the banks of the Paro (or Pa) Chhu, just a short distance northwest of the imposing Paro Dzong.
The Bumthang region encompasses four major valleys: Chokhor, Tang, Ura and Chhume.
Near the foot of the Chokhor valley, Jakar (or Chakkar) is the major trading centre of the region.
Unless they are making an overland crossing to or from India, most Western travellers tend to give Chhukha Dzongkhag a wide berth.
Upper Paro Valley
Though the Paro valley extends west all the way to the peaks on the Tibetan border, the road only goes as far as Drukgyel Dzong, 11km beyond Paro.
The small, sweltering border town of Phuentsholing sits opposite the much larger Indian bazaar town of Jaigaon, separated by a flimsy fence and the much- photographed Bhutan Gate.
Trashigang is the heart of eastern Bhutan and was once the centre of important trade with Tibet.
Wangdue Phodrang Dzongkhag
The scenic dzongkhag of Wangdue Phodrang is centred on the town and dzong of that name and stretches all the way to the Pele La and Phobjikha valley.
Trashigang is one of Bhutan's more interesting towns and a good base for excursions to Trashi Yangtse, Khaling, Radi, Phongme and elsewhere in eastern Bhutan.
Trongsa is smack in the middle of the country, a seven-hour drive from Thimphu, and separated from both east and west by high mountain ranges.