Drive the winding road to Drukgyal Dzong, the ruined fortress, which once defended this valley from Tibetan invasions. Continue to Ramthangkha, from where you will hike up to the Taktsang monastery (Tiger’s Nest), which clings to the rocks towering 2600 feet above the valley. On the way back, visit Kychu Lhakhang, the oldest Buddhist temple in Bhutan, built in the 7th century by the first king of Tibet. Also explore Paro Rimpung Dzong, one of Bhutan’s most impressive and well-known temples. Walk from the Dzong to the old traditional covered wooden bridge and stroll along the west bank of the river.