Entering the centre pier through an arched way, you pass into a spacious circular area, and ascend with an easy grade, by a railway, to the grand terrace, 75 feet above the base of the Monument. This terrace is 700 feet in circumference, 180 feet wide, enclosed by a colonnaded balustrade, 15 feet high with its base and capping. The circuit of this grand terrace is studded with small temple-formed structures, constituting the cupolas of the lanterns, lighting the Pantheon gallery below; by means of these little temples, from a gallery within, a bird's eye view is had of the statues, &c., below. Through the base of the great circle of the balustrade are four apertures at the four cardinal points, leading _outside_ of the balustrade, upon the top of the main cornice, where a gallery 6 feet wide and 750 feet in circumference encircles the whole, enclosed by an ornamental guard, forming the crowning member on the top of the tholus of the main cornice of the grand colonnade. Within the thickness of this wall, staircases descend to a lower gallery over the plafond of the proanos of the colonnade lighted from above. This gallery, which extends all round the colonnade, is 20 feet wide--divided into rooms for the records of the monument, works of art, or studios for artists engaged in the service of the Monument. Two other ways communicate with this gallery from below. In the centre of the grand terrace above described, rises the lofty obelisk shaft of the Monument, 50 feet square at the base, and 500 feet high, diminishing as it rises to its apex, where it is 40 feet square; at the foot of this shaft and on each face project four massive zocles 25 feet high, supporting so many colossal symbolic tripods of victory 20 feet high, surmounted by fascial columns with their symbols of authority. These zocle faces are embellished with inscriptions, which are continued around the entire base of the shaft, and occupy the surface of that part of the shaft between the tripods. On each face of the shaft above this is sculptured the four leading events in General Washington's eventful career, _in basso relievo_, and above this the shaft is perfectly plain to within 50 feet of its summit, where a simple star is placed, emblematic of the glory which the name of WASHINGTON has attained. To ascend to the summit of the column, the same facilities as below are provided within the shaft, by an easy graded gallery, which may be traversed by a railway, terminating in a circular observatory 20 feet in diameter, around which at the top is a look-out gallery, which opens a prospect all around the horizon.