Ground was broken for the foundation of the Lincoln Memorial on February 12, 1914. The work was divided into two parts, a sub- and an upper-foundation. Because the memorial was to be built on drained and filled land, extra care had to be taken with the foundation for such a massive structure.
The sub-foundation is made up of 122 solid, poured concrete piers with steel reinforcing rods anchored in bedrock. The upper-foundation is a second series of piers resting on the primary columns. The top piers are all joined together by poured concrete arches that form the floor of the memorial, later covered with a sheathing of marble.
All foundation work was completed in May 1915. Earlier that year work had started on the main structure itself and fill was brought in to build up the the circular mound that would be the landscape setting for the memorial. Work continued at a steady pace until April 1917, when the United States entered World War I. Work slowed considerably because of labor and material shortages but never came to a halt. In 1918, after all parties agreed that the statue of Lincoln would have to be doubled in size so that it would not appear lost in the building, steel struts were added beneath the floor to support the added weight from the larger statue.
From the chamber of the memorial, one can appreciate the different stones used in its construction. The terrace walls and lower steps comprise granite blocks from Massachusetts - the upper steps, outside facade, and columns contain marble blocks from Colorado - the interior walls and columns are Indiana limestone - the floor is pink Tennessee marble - the ceiling tiles are Alabama marble – and the Lincoln statue comprises 28 pieces of Georgia marble. These building materials may seem random, but Henry Bacon specifically chose each one to tell a very specific story. A country torn apart by war can come together, not only to build something beautiful, but also explain the reunification of the states.
Once the roof was on, decorative murals were painted on the tops of the south and north walls and the Gettysburg Address and the Second Inaugural were carved into the stone beneath the paintings.
In December 1919 and January 1920 the statue of Lincoln was assembled and completed. Periodically during the project, the structure was inspected for settling. When necessary, repairs were made and walls and foundations strengthened. Throughout 1921 roadways and walks were built. Trees and shrubberies were planted, lawns seeded, and huge, old boxwoods were transplanted to the memorial grounds.
Work began, too, on the Reflecting Pool between the Lincoln Memorial and the Washington Monument. By the time of the dedication on May 30, 1922, all the work was done except for completing the pool and the interior lighting which were finished within the next few years.