Timeline: from watchtower to the most significant historic monument in Abu Dhabi

Qasr Al Hosn started out as a watchtower in 1760 on the island of Abu Dhabi, and grew in proportion and significance over the centuries.

Undated photo of Qasr Al Hosn fort in Abu Dhabi, UAE. Courtesy Qasr Al Hosn

1760-61: Fresh water is found on the island of Abu Dhabi and Sheikh Dhiyab bin Isa, leader of the Bani Yas tribe, orders the building of a watchtower.

1795: Sheikh Shakhbut bin Dhiyab takes up residence on the island and begins construction of a fort.

1818-33: David Wilson, British Resident in the Gulf, reports that 'the fort, although neat, is but small, indeed it is little better than a fortified house'.

1845-55: Sheikh Saeed bin Tahnoon greatly expands the fort, turning it into a two-storey building.

1901: Fort is photographed for the first time by Samuel Zwemer, an American missionary who describes visiting Sheikh Zayed bin Khalifa's 'imposing castle'.

1939: Sheikh Shakhbut bin Sultan uses some of the first oil revenue to fund expansion, enclosing the old walls with a larger structure that still remains.

1958: Samples of the first oil from the Das Island exploration base are brought to Sheikh Shakhbut in his Qasr Al Hosn majlis.

1966: After the accession of Sheikh Zayed bin Sultan as Ruler of Abu Dhabi, the fort ceases to be the Ruler's residence and is used for administration.

1980s: Renovation, including the construction of a new two-storey building on the site of a 19th-century structure.

2008: Fort is closed to the public in preparation for major restoration.

2013: First Qasr Al Hosn Festival.

2014: Second Qasr Al Hosn Festival allows visitors to inspect parts of the structure under renovation.