Washington D.C. is the capital of the United States of America (USA), from 1790.

The city is positioned in the center of the nation, The city is situated on the north bank of the Potomac River, and is bordered by the states of Virginia to the southwest and Maryland to the other sides.

The project was entrusted to a French General, Pierre Charles L'Enfant (1754-1825). He introduced Baroque monuments, very similar to the urban structure of Versailles. In his plan L'Enfant defines two very large axes east-west and North-South, and two buildings located at the ends: The United States Congress (seat of parliament and the legislature) in the east and the White House (residence of the President) in the North. The two axes, situated in green parks, are perpendicular to each othe, in the point of intersection was placed a statue of President Washington.

Compared the two axes, the city has a dense mesh of streets orthogonal. But this shirt is superimposed on a pattern of diagonal streets, the avenues, who identifying a system of fifteen squares (one for each state of the union) and linking the most important places of the city. The Pennsylvania Avenue, particularly, connects also visually the Unite States Congress withe the White House.