Pan American Union Building
The Pan American Union Building is the headquarters for the Organization of American States. It is located at 17th Street N.W. between C Street N.W. and Constitution Avenue, Northwest, Washington, D.C.History
On the former site of the John Peter Van Ness Mansion. The cornerstone was laid on May 11, 1908, by Theodore Roosevelt, Elihu Root, and Andrew Carnegie, and the building was dedicated on April 26, 1910.
In 1919, the initial meeting of the International Labour Organization was held in the building.
In 1969, the building was added to the National Register of Historic Places.