Sheffield is a city and metropolitan borough of South Yorkshire, England. Its name derives from the River Sheaf, which runs through the city. Historically a part of the West Riding of Yorkshire, the city has grown from its largely industrial roots to encompass a wider economic base. The city is in the eastern foothills of the Pennines, and the valleys of the River Don and its four tributaries, the Loxley, the Porter Brook, the Rivelin and the Sheaf. 61% of Sheffield's entire area is green space, and a third of the city lies within the Peak Districtnational park. There are also many wonderful parks, woodlands and gardens in the city, and an estimated 2 million trees, giving Sheffield the highest ratio of trees to people of any city in Europe. The city has a long sporting heritage, and is home to the world's oldest football club.