Unveiling the history beneath the Lincoln Memorial

To call Washington a "swamp" is a metaphor, but also the literal truth. So, when planning began for the Lincoln Memorial in the early 1910s, builders faced a real sinking problem. Their solution led to one of Washington's best-kept secrets, hidden for over a century … until now. Underneath the Lincoln Memorial is what's known as the memorial's Undercroft (a term usually reserved for the vaulted basement of a medieval castle or cathedral). Here, 120 massive concrete pillars sink 50 feet into the ground, down to the bedrock, to support the weight of the marble above. The Undercroft, constructed to support the weight of the Lincoln Memorial above. CBS News The entire space, 50,000 square feet (almost twice the size of the memorial above), has never been seen by the public before, said Secretary of the Interior Doug Burgum. He also pointed out the stalactites: "They're still dripping. And of course, as the rainwater comes through cracks in the granite, it seeps down here, picks up calcium," he said. Visitors will be able to see it for themselves starting this June, in a new museum hanging directly beneath the memorial. "I thought it would be a good idea just to have more of an educational role for the Lincoln Memorial," said philanthropist David Rubenstein, who helped bring the Undercroft out of the shadows, donating a quarter of the $69 million needed for its transformation. …