As befits its status as the United States' capital city, Washington DC has a series of speedy, mass transit underground trains, collectively known simply as the 'Metro'. These trains transport passengers to and from many of the more interesting areas of the DC metropolitan area. They also run to useful places such as Reagan National Airport and the large business/shopping district of Tyson's Corners.
There are five lines to the Metro. The individual lines are designated by colours - Blue, Green, Red, Yellow, and Orange - and now all of the stations have signs that show which color trains are coming next, and how many minutes they are away. The lines run out into the states of Virginia and Maryland, and are run by WMATA, the Washington Metropolitan Area Transportation Authority. For a minimum fare, you too can be sped around the District while trying to figure out where you should have transferred to the Yellow Line, and why the hell you are now in the State of Maryland.
Some of the more interesting stations include:
At the intersection of the Blue, Orange, and Red lines, north of the National Mall, lies one of the largest stations on the Metro line. Built on two underground levels with a connecting department store, this is where all innovations on the Metro line began, such as newer and fancier cards/tickets. Alas, you have to keep returning to Metro Center to upgrade these as it takes a while for the latest technology to spread around the system. This station is also the home of the prestigious Metro Gift Store, where you can buy t-shirts, mouse pads, mugs, and just about anything else they can slap the Metro map on to entice the travelling public to part with their money. Don't expect to be able to take a full mug on to the trains. No food or drinks are allowed to be consumed once you are aboard.
Federal Triangle and Smithsonian Stations
The next two stations southbound out of Metro Center on the Blue/Orange line, these are on the north and south sides of the National Mall, and perhaps see more traffic than any other station, especially during large events such as the 4 July and other national celebrations. If you are planning to attend one of these functions, it would be best to be patient, or be willing to hike a bit to a station of one of the other three colours.
It is unknown who decided that the best place to create a transfer point between the Blue and Yellow lines would be under the largest office building in the world, and the hub of the US Military. As it stands, though, this station offers an interesting mixture of life as military officers, civilian military employees, and generic civilians mill about waiting for the next train. Oddly, this is the only station in the Metro system with a signal displaying the colour of the next train approaching the station.
The Yellow Line
This is the appendix of the Washington DC Metro system. One has to look hard to find a Yellow Line station, as most of them are Blue/Yellow or Green/Yellow. In fact there are only two stations that are purely Yellow Line, both just a stone's throw south of King Street where the line combines with the Blue line. At the Pentagon it then splits, goes under the Potomac (where you'll find the southern crossing), and meets up with the Green Line at L'Enfant Plaza. From there it meanders north about a mile before stopping in the middle of the District, as though realising how futile and laughable its presence is.
A Final Point...
The Dupont Circle station is closest to the Common Share, though the Woodley metro stop - or Woodley Park-Zoo/Adams Morgan, to give it its full name - is nearby, on the corner of 18th and 'U'). Some might describe the Common Share as 'the finest pub in Washington DC/Maryland/Virginia, or even, possibly, the finest pub in all of the midatlantic states', though others would merely concede that the pints of Guinness and Boddingtons there are really cheap. If this doesn't take your fancy, try The Brickskeller (also near Dupont Circle), which has a better pub atmosphere and 1100 kinds of beer. There are many other good bars on 18th St as well, in the Adams Morgan neighborhood.