Under the chair of Lincoln

 

Here's an interesting article about the upgrades being performed under the Lincoln Memorial in Washington, D.C.  In a very small visitor space on one side of the memorial, there was a window allowing a view into the space (which the article calls the 'undercroft'), and you could see some stalactites, as some of the marble has been dissolved by rainwater and then redeposited.  They are using some of this big space now.

Beneath the Lincoln Memorial, a vast space is being transformed

"The 38,000-ton structure was built on a platform supported by 122 concrete pillars that were sunk through the soft earth to the solid rock below. Dirt was packed around that foundation, leaving about 50,000 square feet of empty undercroft beneath the memorial.

The undercroft is so large that the entire memorial, flipped upside down, would fit in it, said Sam Meyerhoff, senior project manager with the Consigli construction company, which is doing much of the project work."

Below is what the work will look like.

Read more about the project here.