Ok, so it's not his tomb but it is his memorial. The one in Kentucky not DC. I was up there on business and stopped by Lincoln's birthplace. It's a national park and was bought in 1894 by a businessman who wanted to make money putting Abe's log cabin on display.
The interesting part of the visit was finding out that the Lincoln log cabin really wasn't Abe's. In fact it was one that also traveled the country as part a commemoration for Jefferson Davis, the President of the Confederate States of America.
So the guy made money charging people to view it and it was marketed as both Lincoln's birthplace and that of Jefferson Davis.
When the country decided to create a memorial for
There wasn't a log cabin on the property so they bought this one that had traveled as part of the show.
It was installed in the memorial building and for over 80 years was thought to be Abe's. In 2004 testing was done on it by the University of Tennessee that proved it was not old enough to be Lincoln's or Davis's. The testing showed the wood to be from the 1840s.