At the time of its construction, it was the tallest building in the world. It is still the tallest building in Washington D.C.
Its cornerstone was laid on July 4, 1848; the capstone was set on December 6, 1884, and the completed monument was dedicated on February 21, 1885.
Construction was halted due to financial problems, the American Civil War and other reasons. When construction resumed, the stones used to proceed were taken from a different quarry and have a slightly different color than the bottom third of the obelisk.