Qasr al-Hosn, Historical fort in Abu Dhabi, United Arab Emirates.

Qasr al-Hosn is Abu Dhabi's oldest stone building, begun in 1761 as a conical watchtower and enlarged into a fort in 1793. Its flat-roofed white ranges are broken by projecting towers with rounded battlements, pierced by tall arched openings and small slit windows; a cylindrical tower with a wider battlemented top stands at one corner.

The structure was built in 1761 as a watchtower to protect Abu Dhabi's only source of fresh water at the time. It gradually expanded over the decades into a larger fortification and the residence of the ruling family.

The House of Artisans, part of the Al Hosn complex, presents traditional Emirati crafts and runs educational workshops and events. Demonstrations cover Sadu weaving, Khoos palm-frond work and Talli embroidery. The Qasr Al Hosn Festival, an annual 11-day event on the fort grounds, adds live music and dance performances.

The fort stands on Rashid Bin Saeed Al Maktoum Street, within the Al Hosn complex alongside the Cultural Foundation and the House of Artisans. Some areas stay closed outside the annual 11-day Qasr Al Hosn Festival, when restricted sections open and performances are staged on the grounds. The nearby Zayed the Second Mosque on Zayed the First Street is a separate building from the Grand Mosque.

The fort was not originally white: it was painted bright white during renovations between 1976 and 1983, which is why it is known as the White Fort. Its 1761 core began as a conical watchtower guarding Abu Dhabi island's only freshwater well.