M25

The motorway forming a ring around Greater London. Built in a vain attempt to remove through-traffic from central London, it simply increased the number of vehicles on the road to such a point that to Londoners the M25 is known as "Britain's biggest car-park"

In Messier's List M 25 is also the magnitude 4 open cluster located 2,000 light years away at R.A. 18:16.9 and Dec. -18°29, between the head & the end of the bow of the constellation Sagittarius. M 25 contains over 100 stars, and is about 23 light years across.

The cluster also contains one bright Cepheid variable, U Sagittarii which fluctuates from 6.3 to 7.1 magnitude over a period of 6.75 days.

An alternative name for the M25 is the "London orbital car-park". It tends to live up to this name on Friday evenings such as tonight, when large segments are so congested that it would be almost as fast to walk - if walking were allowed on Britain's motorways.

The major advantage is when you know one or more alternative routes, which are (relatively) free of traffic, due to the less knowledgeable drivers being on the M25.