Bristol is a city and county in South West England with a population of 449,300 in 2017. The district has the 10th largest population in England, while the Bristol metropolitan area is the 12th largest in the United Kingdom. The city borders North Somerset and South Gloucestershire, with the cities of Bath and Gloucester to the south-east and north-east, respectively. Iron Age hill forts and Roman villas were built near the confluence of the rivers Frome and Avon, and around the beginning of the 11th century the settlement was known as Brycgstow. Bristol received a royal charter in 1155 and was historically divided between Gloucestershire and Somerset until 1373, when it became a county of itself. From the 13th to the 18th century, Bristol was among the top three English cities after London in tax receipts. Bristol was surpassed by the rapid rise of Manchester, Liverpool and Birmingham in the Industrial Revolution. Bristol was a starting place for early voyages of exploration to the New World. On a ship out of Bristol in 1497 John Cabot, a Venetian, became the first European since the Vikings to land on mainland North America. In 1499 William Weston, a Bristol merchant, was the first Englishman to lead an exploration to North America. At the height of the Bristol slave trade, from 1700 to 1807, more than 2,000 slave ships carried an estimated 500,000 people from Africa to slavery in the Americas. The Port of Bristol has since moved from Bristol Harbour in the city centre to the Severn Estuary at Avonmouth and Royal Portbury Dock. Bristols modern economy is built on the creative media, electronics and aerospace industries, and the city-centre docks have been redeveloped as centres of heritage and culture. The city has the largest circulating community currency in the U.K.- the Bristol pound, which is pegged to the Pound sterling. The city has two universities, the University of the West of England and the University of Bristol and a variety of artistic and sporting organisations and venues including the Royal West of England Academy, the Arnolfini, Spike Island, Ashton Gate and the Memorial Stadium. It is connected to London and other major UK cities by road, rail, sea and air by the M5 and M4, Bristol Temple Meads and Bristol Parkway mainline rail stations, and Bristol Airport. One of the UKs most popular tourist destinations, Bristol was selected in 2009 as one of the worlds top ten cities by international travel publishers Dorling Kindersley in their Eyewitness series of travel guides. The Sunday Times named it as the best city in Britain in which to live in 2014 and 2017, and Bristol also won the EUs European Green Capital Award in 2015.