I remember when we took the train (Eurostar) to across the English Channel from Paris to London, it was a disaster and quite exhilarating.
When we traveled between European countries, we never had to present our passports or go through customs because all the countries belong to the Euro zone. We naively thought the same when traveling to UK. I think technically UK is part of the European Union, but for some reason, it requires its own customs and checking. Anyway, we miss-timed our schedule because we didn't know we had to go through customs. As a result, we almost missed our train.
Similar to Paris, the first attraction that I visited in London is a Grand Slam tennis tournament, Wimbledon. The place wasn't quite far and we just needed to take the right public transit to reach there.
Here is Court 1.
Murray Mountain (used to call Henman Hill)
The longest match ever played in history.
The beautiful centre court.
After immersing myself with Wimbledon, we traveled to the city centre and saw the biggest landmark that captured our eyes - The London Eye.
And then we see the Big Ben.