The fortress-monastery that dominates the Paro valley, completed in 1646 and still in use as both a working monastery and the seat of the district's civil administration. It is one of the most photographed buildings in Bhutan: a massive whitewashed structure with sloping walls, a central tower, and intricately painted woodwork around every window and balcony. The interior central courtyard is paved in stone, lined with murals, and quiet enough that you can usually hear the resident monks chanting somewhere in the building.
A traditional cantilevered wooden bridge over the Paro Chhu river leads up to the entrance. The annual Paro Tsechu is held in the dzong's main courtyard in late March or early April; on the festival's final morning the famous thondrol, a giant embroidered scroll showing Guru Rinpoche and his eight manifestations, is unfurled on a wall before dawn. It is rolled away again before the sun touches it, on the belief that simply seeing it confers a blessing equivalent to a lifetime of practice.