The town's main attractions are Gainsborough Old Hall, Gainsborough Castle and West Lindsey Leisure Centre.
Gainsborough Old Hall is a large 15th century timber-framed medieval strong house, it is over 500 years old and is one of the best preserved manor houses in Britain. Sir Thomas Burgh built it between 1460 and 1480. It boast a magnificent Great Hall and strong brick tower. King Richard III in 1483 and King Henry VIII in 1541 both stayed at the Old Hall.
Plans to expand Gainsborough as a new town, linked with Sheffield, never came to fruition, so it remains a small market town. The River Trent runs right along side Gainsborough, and recently the river banks have been renovated to provide residents and tourist with access to the riverside and a sitting area to enjoy the view.
Historically, Gainsborough is the 'capital that never was.' King Cnut allegedly performed his unsuccessful attempt to turn the tide back in the River Trent at Gainsborough, but nevertheless, the town was a capital city of Mercia during the Dark Ages.
Gainsborough is also famed as Britain’s most inland port and so has a long history with river trade — the town’s Trent bridge prevents most barges from go beyond it and so many have to offload their goods at the town.
Gainsborough is thought by many scholars to be the basis for the fictional St Ogg's in George Eliot's The Mill on the Floss.