The M57 Liverpool Outer Ring Road doesn't seem to circumnavigate enough of Liverpool to be called a ring road. Liverpool is, admittedly, on the coast, and a motorway forming a full circle was never really on the cards, but this is little more than a straight line to the east of the city. A route was once planned from the coast north of Liverpool near Southport, down to the Mersey near Widnes, but only the central section was ever built.
In the early 1990s, the route was extended southwards to reach the Mersey, but for some reason it was decided not to extend the M57 (which would have been the obvious thing to do), and instead the road was built as an all-purpose road, the A5300 Knowsley Expressway.
In 2015, a northward continuation was opened to link the M57 to the A565 towards Southport, a new single-carriageway road called the A5758 Broom's Cross Road. This completes the full planned length of Liverpool's outer ring road, but at a much-reduced standard.
For most of its existence, the M57 was entirely disconnected from the wider motorway network. At both ends, it shared a junction with another motorway - M58 in the north and M62 in the south - but there was no way to get to either of them without leaving the motorway and using a short section of all-purpose road through the junction. In December 2008, new free-flow sliproads were opened at junction 1, which for the first time connected the M57 directly to the M62 and made it part of the national motorway network.
The northern terminus of the motorway, Switch Island, was meant to be a large roundabout with a north-south flyover for the M57 and lots of fun free-flow links zooming across the top just for good measure. Only the roundabout was ever built, the rest awaiting work to continue the M57 north and the M58 west, which never happened, and so the roundabout was left to cope with two motorways and three busy dual-carriageways piling into it. The junction has been remodelled several times since then, but always as a flat signal-controlled junction, so it's now made up of fragments of roundabout and lots of traffic lights.