is a cool building. I've taken a tour of it. It used to be the "Pension Building" and gave out pension checks to Civil War survivors, and widows and orphans.
Following the end of the Civil War the United States Congress passed legislation that greatly extended the scope of pension coverage for both veterans and for their survivors and dependents, notably their widows and orphans. This ballooned the number of staff that was needed to implement and administer the new benefits' system to over 1,500 and quickly required a new building out of which to run it all. Meigs was chosen to design and construct the new building and in doing so broke away from the established Greco-Roman models that had been the basis of government buildings in Washington D.C. up until then, as was to continue following the Pension Building's completion. Meigs based his design on Italian Renaissance precedents, notably Rome's Palazzo Farnese and the Palazzo della Cancelleria.
In a period before modern artificial ventilation the building was designed to maximize air circulation. All offices had not only exterior windows, but opened onto the court which was designed to admit cool air at ground level and exhaust hot air at roof level. Constructed of brick and tile the stairs were designed with the limitations of disabled and aging veterans, having a gradual ascent with low steps. In addition, each step slanted slightly from back to front to allow easy drainage- a flight could be easily washed by pouring water from the top.
http://en.wikipedia.org/wiki/National_Building_Museum:hi: