The station building proper is 626 feet 10 inches long and 210 feet 9 inches wide, exclusive of the space taken up by the columns in front of the central pavilion or main portico. The front and ends are made up of groups of semicircular arches characteristic of Roman architecture. The main portico or central pavilion consists of 3 arches, each 29 feet 6 inches wide and 48 feet 9 inches high. Flanking it on either side are 7 arches, each 12 feet 4 inches wide and 24 feet 8 inches high, while the end pavilions are composed of arches 22 feet wide and 38 feet 6 inches high. The west end is made up of 5 arches 19 feet 2 inches wide and 37 feet 7 inches high, and 1 arch 12 feet 4 inches wide and 24 feet 8 inches high. The former are used as exits for carriages from the carriage porch, the latter to carry out the open portico treatment across the front. At the east end leading to the open portico are 2 windows with arch treatment, and there are 5 arches 12 feet 6 inches wide and 24 feet 8 inches high, 1 arch 22 feet wide and 38 feet 6 inches high, leading to a carriage pavilion. The east pavilion leads to a suite of rooms for the use of the President and the guests of the Nation, the west pavilion to the carriage porch at the west end of the ticket lobby. The central and end pavilions are connected by a portico or loggia from 14 feet 6 inches to 16 feet 6 inches wide, the portico and pavilions forming a continuous covered porch the entire length of the structure, and affording protection from the elements. The east and west wings of the building are 69 feet 7¹⁄₂ inches above the floor level, and the domes over the carriage entrances are 78 feet 3¹⁄₂ inches above the same point. The dome over the main waiting room is 122 feet 10 inches high. [Illustration: UNION STATION--WAITING ROOM] The concourse in the rear of the main building is 760 feet long and 130 feet wide, exceeding by nearly nine feet the length of the Capitol. It is covered by a segmental arched ceiling 45 feet high in the center and 22 feet at the springing line above the main floor. About 40 per cent of the ceiling area is of glass, the remainder is artistically coffered ornamental plaster. The concourse is divided by the usual train fence into two sections, that on the station side being 83 feet and that on the track side 47 feet wide. There are 32 tracks leading to the station--20 on the level of the waiting rooms and 12 depressed below the street level a distance of 20 feet. Two tubes of the Pennsylvania Railroad Co. and Southern Railway Co., each 16 feet wide, run from the station south along First Street between the Library of Congress and the Capitol for about a mile. At the Fountain of Neptune the tunnel is 40 feet below the surface. Approximately 285 trains enter and leave the railway station each day; the daily number of passengers is approximately 30,000.