Geography of Sheffield (Totley Brook passes south of Totley and meets Old Hay Brook at Needham's Dyke). The Sheaf flows northwards to join the River Don near Blonk Street Bridge in the city centre. This lower section of the River Sheaf together with the River Don, between the present Blonk Street and Lady's Bridge, formed part of the perimeter of Sheffield Castle. Porter Brook's source is just inside the Peak District National Park, to the west of the city, at Clough Hollow, also near Ringinglow. From here it flows eastward to meet the Sheaf, at a point now located underneath Sheffield Midland Station.
Sheffield City Centre of the city centre, is host to numerous national and international sporting events, notably swimming and Basketball. The Crucible Theatre, in Tudor Square, is host to the World Snooker Championships which have been held there since 1977. Sheffield is home to the greatest concentration of theatres in the UK outside London. These include the Crucible, Lyceum, Montogomery and Studio theatres. The city centre is home to numerous venues which attract many well-known musicians, comedians, theatre groups and so on. Examples include the City Hall, O2 Academy, Plug, and the Lyceum and Crucible theatres. Sheffield city centre is host to its