An unusual opportunity has emerged to snap up not one, but two, coveted and historic townhouses in London that are ready to be transformed into a palatial megamansion. The pair, which combined span more than 9,000 square feet, are asking for offers in excess of £20 million (US$27.1 million) and are perfectly primed for a high-end overhaul, according to Marc Schneiderman, director of Arlington Residential, which listed the properties last week.