From these radiate broad avenues, called after the names of States, which in turn are cut by a repetition of streets, running east and west, and by another series, running north and south; the odd-shaped spaces, formed by the intersection of these streets with the avenues, being utilised as little public gardens. Thus Washington is a city of beautiful breathing spaces, its gardens, parks, and tree-bordered avenues comprising one-half of its total area. The first official building was the =Treasury=, which was commenced in 1781 by Robert Mills, who held the position of United States Architect. The design, as completed, presents an imposing rectangular mass, the east side of which is masked with a colonnade of 38 Ionic columns, while Ionic porticoes decorate the other three façades. In 1792 work was started on the =White House= and a year later on the =Capitol=. =White House.=--The Executive mansion, designed by James Hoban after the model, it is said, of a seat of the Duke of Leinster near Dublin, consisted of a two story house, surmounted by a balustrade and fronted by an Ionic portico. Even with the additions, made in recent years to serve as Executive offices, it is characterised by a dignified simplicity, befitting the residence of “the first gentleman of the land.” =The Capitol.=--The Capitol is finely placed on a hill some 100 feet above the level of the Potomac River. Its central portion was designed by William Thornton with some modifications suggested by his collaborators, B. H. Latrobe and Charles Bulfinch. The wings and dome were added 1851 to 1865. The main façade is on the east, where three imposing flights of steps lead up to three Corinthian porticoes which indicate the special functions of the building. That on the left, with allegorical sculpture in the pediment by Thomas Crawford, forms the main entrance to the wing occupied by the Senate Chamber, while that on the right, to which sculpture by Paul W. Bartlett has just been added, distinguishes the Hall of Representatives.