Piccadilly Circus
While I was a student in Madrid, Spain, I once asked a friend from London, England what Piccadilly Circus was like. Her instant reply, "SOL!"
By Sol she meant Madrid's Puerta del Sol which was and continues to be a very lively square in the middle of the city center.
Although it was gray when we got to Piccadilly, the atmosphere was quite electric. There were tons of happy tourists taking pictures. I actually thought it looked more like New York's Times Square albeit in a smaller scale. There were electronic billboards and theaters nearby.
This trip to Piccadilly gave me a better idea of the lay of the land. While I remembered a lot about London from our first visit 17 years ago, I had forgotten that it was just steps away from Regents Street and not that far away from Leicester Square either.