SS Great Britain is a museum ship and former passenger steamship that was advanced for her time. She was the largest passenger ship in the world from 1845 to 1854. She was designed by Isambard Kingdom Brunel (18061859), for the Great Western Steamship Company's transatlantic service between Bristol and New York City. While other ships had been built of iron or equipped with a screw propeller, Great Britain was the first to combine these features in a large ocean-going ship. She was the first iron steamer to cross the Atlantic Ocean, which she did in 1845, in 14 days.

The ship is 322 ft (98 m) in length and has a 3,400-ton displacement. She was powered by two inclined two-cylinder engines of the direct-acting type, with twin high pressure cylinders (diameter uncertain) and twin low pressure cylinders 88 in (220 cm) bore, all of 6-foot (1.8 m) stroke cylinders. She was also provided with secondary masts for sail power. The four decks provided accommodation for a crew of 120, plus 360 passengers who were provided with cabins, and dining and promenade saloons.

When launched in 1843, Great Britain was by far the largest vessel afloat. But her protracted construction time of six years (18391845) and high cost had left her owners in a difficult financial position, and they were forced out of business in 1846, having spent all their remaining funds refloating the ship after she ran aground at Dundrum Bay in County Down near Newcastle in what is now Northern Ireland, after a navigation error. In 1852 she was sold for salvage and repaired. Great Britain later carried thousands of emigrants to Australia from 1852 until being converted to all-sail in 1881. Three years later, she was retired to the Falkland Islands, where she was used as a warehouse, quarantine ship and coal hulk until she was scuttled in 1937, 98 years after being laid down.In 1970, after Great Britain had been abandoned for 33 years, Sir Jack Arnold Hayward, OBE (19232015) paid for the vessel to be raised and repaired enough to be towed north through the Atlantic back to the United Kingdom, and returned to the Bristol dry dock where she had been built 127 years earlier. Hayward was a prominent businessman, developer, philanthropist and owner of the English football club Wolverhampton Wanderers. Now listed as part of the National Historic Fleet, Great Britain is a visitor attraction and museum ship in Bristol Harbour, with between 150,000 and 200,000 visitors annually.

Isambard Kingdom Brunel (; 9 April 1806 – 15 September 1859) was an English civil engineer who is considered "one of the most ingenious and prolific figures in engineering history," "one of the 19th-century engineering giants," and "one of the greatest figures of the Industrial Revolution, [who] changed the face of the English landscape with his groundbreaking designs and ingenious constructions." Brunel built dockyards, the Great Western Railway (GWR), a series of steamships including the first propeller-driven transatlantic steamship, and numerous important bridges and tunnels. His designs revolutionised public transport and modern engineering.

Though Brunel's projects were not always successful, they often contained innovative solutions to long-standing engineering problems. During his career, Brunel achieved many engineering firsts, including assisting in the building of the first tunnel under a navigable river (the River Thames) and the development of the SS Great Britain, the first propeller-driven, ocean-going iron ship, which, when launched in 1843, was the largest ship ever built.On the GWR, Brunel set standards for a well-built railway, using careful surveys to minimise gradients and curves. This necessitated expensive construction techniques, new bridges, new viaducts, and the two-mile-long (3.2 km) Box Tunnel. One controversial feature was the "broad gauge" of 7 ft 1⁄4 in (2,140 mm), instead of what was later to be known as "standard gauge" of 4 ft 8+1⁄2 in (1,435 mm). He astonished Britain by proposing to extend the GWR westward to North America by building steam-powered, iron-hulled ships. He designed and built three ships that revolutionised naval engineering: the SS Great Western (1838), the SS Great Britain (1843), and the SS Great Eastern (1859).

In 2002, Brunel was placed second in a BBC public poll to determine the "100 Greatest Britons." In 2006, the bicentenary of his birth, a major programme of events celebrated his life and work under the name Brunel 200.