Grand Turk is an island in the Turks and Caicos Islands, a British Overseas Territory, tropical islands in the Lucayan Archipelago of the Atlantic Ocean and northern West Indies. It is the largest island in the Turks Islands (the smaller of the two archipelagos that make up the island territory) with 18 km (6.9 sq mi). Grand Turk contains the territory's capital, Cockburn Town, and the JAGS McCartney International Airport. The island is the administrative, historic, cultural and financial centre of the territory and has the second-largest population of the islands at approximately 4,831 people in 2012.

The name comes from a species of cactus on the island, the Turk's cap cactus (Melocactus intortus), which has a distinctive cap, reminiscent of an Ottoman fez. In addition, this interpretation of the name received a reaction in the Turkish press on the grounds that it was anachronism. Fez began to be used by the Ottoman Turks in the 19th century, and the "Turk" in the island's name dates back to very old times.

The Lucayan people were the indigenous people of the island, who called it Abawana, meaning "the First Small Land". The Spanish later called it Amuana.

Grand Turk was first colonised in 1681 by Bermudians, who set up the salt industry in the islands. In 1766 it became the capital of the country. For some time, at least until the early 19th century, Grand Turk was often referred to as Grand Cay, not to be confused with either Grand Cay in the Bahamas or Grand Cayman.

Grand Turk Lighthouse was erected in 1852 near northern end of the island. The 60 ft (18 m) lighthouse was designed by Alexander Gordon and built by Chance Brothers in England. It was shipped in pieces and assembled on Grand Turk.

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  Grand Turk's lighthouse, on the northeastern tip of the island

Grand Turk has been put forward as the possible landfall island of Christopher Columbus during his first voyage to the New World in 1492. San Salvador Island or Samana Cay in the Bahamas is traditionally identified with Guanahani, the site of Columbus' first landfall, but some believe that studies of Columbus' journals show that his descriptions of Guanahani much more closely fit Grand Turk than they do other candidates. Magnetic variations that caused misreadings in Columbus' compasses demonstrate that several of the recorded moorings using a rope-secured anchor to a clear sandy bottom would not have been possible had Columbus sailed from the islands of the Bahamas. In addition, the latitudes recorded in Columbus' diary place the landfall island at 90 nautical miles (100 mi; 170 km) from Hispaniola, too close for the Bahamas, but almost exactly the distance from Grand Turk.

On the contrary, historian Gregory McIntosh has concluded that Grand Turk was not Guanahani but Babueca, an island separately discovered by Martín Alonso Pinzón in November - December 1492.

A U.S. Naval Facility (NAVFAC), the name given for a shore terminus of an offshore surveillance array of the Sound Surveillance System (SOSUS), was established on Grand Turk in 1954 as one of three additional Atlantic systems installed that year during the first phase of SOSUS installation. The facility was commissioned 23 October 1954 and was active until decommissioned 31 March 1980. The actual undersea surveillance mission of the system and shore facility remained classified through decommissioning. The NAVFAC was located (21°30′43.6″N 71°07′57.7″W / 21.512111°N 71.132694°W / 21.512111; -71.132694) near the Grand Turk Lighthouse.

Grand Turk, located about 700 nmi (810 mi; 1,300 km) from Cape Canaveral, became the first down range tracking facility of the U.S. Air Force's Eastern Range to have a Missile Impact Location System (MILS) target array to detect the splash down location of test missile nose cones. The next target arrays down range were located at 1,300 nmi (1,500 mi; 2,400 km) at Antigua and at 4,400 nmi (5,100 mi; 8,100 km) at Ascension Island. In addition to the precise target array the facility was the terminus of one of the Broad Ocean Area (BOA) MILS that could give good location data over large ocean areas.

From 1957 to 1959 USN Mobile Construction Battalion 7 constructed a LORAN Station on the island.

In 1962, John Glenn's Friendship 7 Mercury spacecraft landed in the vicinity of Grand Turk off the southeast shoreline. A replica of the Friendship 7 is on display in Grand Turk at the entrance to the Grand Turk airport.

In 1966 at least five Arcas (All-Purpose Rocket for Collecting Atmospheric Soundings) sounding rockets were launched from Grand Turk by the USA.

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  Looking north along Cockburn Town Beach, near the south end of Duke St.
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  Replica of the Friendship 7
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  Looking east at Columbus Landfall Beach, near JAGS McCartney International Airport

• Grand Turk Parade Ground

• Grand Turk - Visit Turks and Caicos Islands
• Grandturk.tc
• Grand Turk Chamber of Commerce
• Grand Turk travel guide from Wikivoyage