The subway to Charing Cross station has an amazing array of mural tiles. Amazing not only aesthetically but amazing because they show a brief but concise history of the nearby locale, how the place was built, what took place. The whos, the whats, the wheres, and the whys were more or less dealt with by the history in tiles.
Walking through the tunnel and underground is interesting and informative, the thing to while away the time when waiting for the next tube, especially when there are some delays.
It is also good for tourists and visitors alike to note what to expect outside or why outside became what it is.