Of all the days to arrive in the world's most cosmopolitan city, Christmas Day is the worst. How do I know? Because that is the day I arrived. There is no public transportation system available. As a result, the taxi drivers can charge an arm and a leg to get you from Heathrow Airport to anywhere in the city.
The best thing to do in that case is spend a few minutes at the airport ground transportation area and make a number of phone calls to the mini-taxis offices and haggle for the best deal. We were able to book a mini-taxi for €25 instead of the €60 that the drivers were charging just outside the airport doors.
That being said, the rest of the week was spectacular. London is such an impressive and grandiose place, that a week there is nowhere close to enough time to get a good handle on the place. Also, coming from California as we were, we felt the public transportation system there was nothing short of first class, even with the reduced service between Boxing Day and New Year's.
I found London's ability to juxtapose the old with the new to be one of its most charming facets. It is interesting to be sitting in one of the enclosed capsules of the modern London Eye Ferris Wheel built at the turn of the second millennium and look across the Thames to Westminster Abbey that was constructed a thousand years before.
There are only a small handful of cities in the world that work on many levels all at once: historical, cultural, financial, and spiritual. London certainly falls into this category and will probably continue to do so for years to come.