The iconic aboveground space at the Lincoln Memorial is accompanied by lesser-known environs beneath—in the form of an “undercroft” being transformed into a 15,000-square-foot exhibition space scheduled to open next month with a show related to the memorial’s creation and the legacy of Abraham Lincoln himself. As reported by Artnet News , “A decade on from the National Park Service (NPS) announcing plans to transform the cavernous space beneath the Lincoln Memorial into a museum, tickets for the newest attraction on the National Mall have gone on sale ahead of its opening on June 25, in time for the 250th anniversary of the Declaration of Independence. Tickets for large tours of the undercroft on opening day are already sold out.” Related Articles The new initiative, said to cost $69 million, started with $18.5-million gift from philanthropist David M. Rubenstein to the National Park Foundation in 2016.…