The Holme, an iconic mansion in London’s posh Regents Park, has gone on sale as the priciest-ever house (in London and worldwide) for a staggering $295 million. The 205-year-old mansion was built by English architect James Burton and designed by his son, Decimus Burton, in 1818. The Holme residence includes 40 bedrooms in 8,840 square meters of living space.