It has played host to countless world leaders and moments in history. Now US President Donald Trump has built a huge cage-fighting arena on the White House’s South Lawn.Cranes lifted giant metal arches into place Tuesday for the Ultimate Fighting Championship (UFC) event on Trump’s 80th birthday on June 14.“We’re having a big fight. It’s never going to happen again, never happened before,” Trump said at an Oval Office event earlier this month, surrounded by four of the fighters taking...