The following is a list and brief history of the bridges in Cambridge, England, principally those over the River Cam of which there are 25, soon to be 26. The River Cam enters Cambridge from the south west of the city and heads north past many of the historic colleges of the University of Cambridge along the open area known as The Backs. After passing St John's College, it turns sharply and runs east, passing the weir at Jesus Green and the boathouses alongside Midsummer Common. Passing Chesterton, it turns north again and leaves the city, running a further before merging with the Great Ouse at Pope's Corner to the south of Ely. Bridges over the River Cam (south to north) Upper River (upstream of mill pond weir) Trumpington Bridge (1790) The most upstream bridge in Cambridge (UK Parliament constituency) lies along Grantchester Road between Grantchester and Trumpington. Also known as Brasel Bridge, this 1790 brick bridge replaced a wooden bridge at the site of a ford. Sheep's Green Footbridge (1910) Links Coe Fen behind The Leys School over a second small bridge to Lammas Land, near the area known as Hobson's Paradise. Also known as Sheep's Green bridge, it was closed in the second quarter of 2006 to replace the steps with ramps to make it easier for cyclists and prams to cross. The bridge decking was also replaced. Fen Causeway Bridge (1926) The first road bridge that is reached as the river enters the city. The road was formally opened on 9 December 1926. Crusoe Bridge (1898–99) A steel footbridge with timber deck and supported on four cast-iron columns, linking Sheep's Green and Coe Fen, and the final bridge on the 'Upper River' before it reaches the small weir at the mill pond. Middle River (between mill pond weir and Jesus Green weir) Darwin College Bridges Two wooden bridges within the college grounds connecting the main site with the college's two islands. Silver Street Bridge (1958) The site of bridges back to the 14th century, a cast iron bridge was built in 1843 but increasing heavy traffic led to a 1913 survey that determined the need for a new bridge. Repairs, however, allowed the bridge to last for a further 40 years. The present wide bridge, clad in Portland stone was designed by Sir Edwin Lutyens in 1932 and built in 1958-9. Mathematical Bridge, Queens' College (1902) This