Buckle up, Bel Air. The City of Angels is once again about to rewrite the record books with a jaw-dropping mega mansion that’s hitting the market, with an asking price that resembles that of a big-budget Hollywood blockbuster: $400 million. If it sells anywhere near that number, this sprawling ultra-luxe estate will become the first residential property in American history to crack the $400 million barrier, shattering previous records and cementing Los Angeles as the undisputed epicenter of over-the-top wealth in the US. The property — a modern palace perched on prime promontory real estate — is the latest symbol of just how insane the ultra-high-end LA housing market has become. Purchased for $35 million in 2010 by a group with ties to Qatar’s ruling Al-Thani family , the estate took 10 years to complete, according to The Wall Street Journal . The 70,000-square-foot spread in Bel Air was designed by famed architect Peter Marino and is listed for $400 million.…