I heard rumors about streams being uncovered here and there, but didn't have details for many. Now I've found the story of the River Quaggy. Read more about it in a delightful book: Rain Gardens by Nigel Dunnett and Andy Clayden.
Sutcliffe Park is a small park located about 10 mi SE of London in the UK. The River Quaggy runs through the park before it empties into the nearby River Thames.
After the nearby suburb of Lewisham suffered from severe flooding, conventional engineering solutions were tried, ending with the burial of the river in an underground, concrete culvert. This led to the loss of natural habitat, as well as fish and wildlife. There was just a flat expanse of soccer fields left after the burial. Still, flooding remained a problem, because confining the stream to such a narrow passage had the effect of creating dam.
To solve the flooding, in 2004 the park was redeveloped and the stream opened to daylight once again. A volume of soil equal to 35 Olympic-sized swimming pools was removed, creating a series of ponds. Now the river flows through the park in a series of meanders exactly as it did over a century ago. The surface of the park was lowered, creating a natural flood plain where floodwaters can collect during severe storms.
"Instead of a ...uniform stretch of metropolitan grassland, there is now a rolling landscape with a range of natural habitats to encourage as much wildlife as possible--the river itself, a lake, ponds (with dipping platform and boardwalks) wildflower meadows (both wet meadows and dry meadows at higher levels), an outdoor classroom, reed beds and a variety of native trees. At the same time, access for the public and for people with disabilities was increased. The scheme has great local support, largely because of the increased wildlife.... Some of the gravelly areas by the river are very popular with children and some people think they have been made deliberately as large play areas, but in fact the children's enjoyment is a by-product of the habitat creation." Photos and more here.
Other streams restored to daylight
Seoul, Korea: Peeling Back Pavement to Expose Watery Havens Blog & pictures here.
See the excellent video about the Korean river restoration (at above link)
Read fascinating comments on the article here.
San Antonio River Walk It's amazing!
Paris: As of 2004, the city was considering uncovering some sections of the River Bièvre.
Charlottesville, VA (at the University of Virginia)
Portland, OR: Tanner Creek
Berkeley, CA: Strawberry Creek & Codornices Creek
Raleigh, NC: Rocky Branch
Charlotte, NC: Little Sugar River Creek
Other river restorations
Saw Mill River, Yonkers, NY plans
The Los Angeles River, which has mostly been straightened and turned into a concrete lined ditch, is being restored in its upper reaches. People kayak on it from time to time.
Naugatuck River in Connecticut