a conditional agreement with the real estate developer Ballymore Group to purchase property for a new embassy site on the South Bank of the River Thames in the Nine Elms area of the London Borough of Wandsworth. The site lies within the Vauxhall/Nine Elms/Battersea Opportunity Area as set out in the London Plan. The proposed plan would only go forward if approved by the United States Congress and by the local planning authority. The Northern line extension to Battersea includes new stations at Battersea and Nine Elms, combined with major local development. The United States Department of State announced in January 2009 that it was choosing among nine architectural firms, all "modern" and "upmarket", to replace the ageing embassy headquarters. In March 2009, the U.S. Department of State's Bureau of Overseas Buildings Operations announced that four architectural firms had been selected for the final phase of the design competition. By law, the architect for a U.S. embassy must be an American firm with "numerous security clearances". In November 2009, the U.S. government conditionally agreed to sell the lease of the Grosvenor Square Chancery Building to Qatari real-estate investment firm Qatari Diar, which in 2007 purchased Chelsea Barracks. Though the price was undisclosed, the lease's worth was estimated at £500 million in July 2000. The development value of the property was reduced when the building was given Grade II listed status, requiring developers to maintain its current design. The building is now one of Mayfair's 238 listed buildings and monuments. In 2016, plans were approved for the conversion of the building into a hotel. On 23 February 2010, the U.S. government announced that a team led by the firm of KieranTimberlake had won the competition to design the new embassy building and surrounding green spaces. The winning design resembles a crystalline cube, with a semi-circular pond on one side (called a "moat" by The Times) and surrounded by extensive public green spaces and the Embassy Gardens housing development. Ground was broken on 13 November 2013, and the building opened to the public on 13 December 2017. US President Donald Trump had been expected to visit in February 2018 to undertake the official opening of the new embassy but, in January 2018, announced he would not make the trip. Trump publicly criticized the cost of the new embassy and its location, as well as the apparent price received for the sale of