Reason I canceled my trip to London is that I am not a big fan of the Obama Administration having sold perhaps the best located and finest embassy in London for “peanuts,” only to build a new one in an off location for 1.2 billion dollars. Bad deal. Wanted me to cut ribbon-NO!— Donald J. Trump (@realDonaldTrump) January 12, 2018
The decision to close the US embassy and move to a new location came under the Bush administration, to address safety and security concerns about the old embassy. The old embassy lease was sold to a real estate developer. The price was reduced because the embassy was designated an architecturally protected landmark.
Widely reported today, the real reason Trump cancelled the trip is that the Brits refused to make this a state visit. The royal family wants no part of honoring Trump. The mayor of London doesn't want to receive Trump, and large protests were expected if Trump showed up.