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The River Sheaf is a river in Sheffield. Its source is the union of the Totley Brook and the Old Hay Brook in Totley, now a suburb of Sheffield. It flows northwards, past Dore, through the valley called Abbeydale. It then passes into a culvert, through which it flows under the centre of Sheffield emerging just once before joining the River Don near Blonk Street Bridge. This lower section of the River Sheaf together with the River Don, between the present Blonk Street and Lady's Bridges, formed two sides of the boundary of Sheffield Castle.
The main tributaries of the Sheaf are the Porter Brook, which joins it beneath Sheffield Midland station, and the Meers Brook. The river used to provide the power for a number of metal works, an important surviving example of which is the Grade I-listed Abbeydale Industrial Hamlet.

The River Don rises on the Pennines and flows 70 miles eastward to join the River Trent.
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Listed buildings and structures are officially designated as being of special architectural, historical or cultural significance. There are over half a million listed structures in the United Kingdom, covered by around 375,000 listings.
Listed status is more commonly associated with buildings or groups of buildings, however it can cover many other structures, including bridges, headstones, steps, ponds, monuments, walls, phone boxes, wrecks, parks, and heritage sites, and in more recent times a road crossing (Abbey Road) and graffiti art (Banksy 'Spy-booth') have been included.

In England and Wales there are three main listing designations;
Grade I (2.5%) - exceptional interest, sometimes considered to be internationally important.
Grade II* (5.5%) - particularly important buildings of more than special interest.
Grade II (92%) - nationally important and of special interest.

There are also locally listed structures (at the discretion of local authorities) using A, B and C designations.

In Scotland three classifications are also used but the criteria are different. There are around 47,500 Listed buildings.
Category A (8%)- generally equivalent to Grade I and II* in England and Wales
Category B (51%)- this appears generally to cover the ground of Grade II, recognising national importance.
Category C (41%)- buildings of local importance, probably with some overlap with English Grade II.

In Northern Ireland the criteria are similar to Scotland, but the classifications are:
Grade A (2.3%)
Grade B+ (4.7%)
Grade B (93%)

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