The principal façade, on St. Louis street, may be generally described as being composed of the Tuscan and Doric orders. The main entrance is formed by six columns of the composite Doric order. Through this portico, access is had to the vestibule of the Exchange, a handsome, though simple hall, 127 by 40 feet. This room is appropriated to general business, and constantly open during waking hours. You pass through this into one of the most beautiful rotundas in America, which is devoted exclusively to business, and is open from noon to three o'clock P. M. This fine room is surrounded by arcades and galleries, always open to the public, (Sundays excepted,) and its general appearance cannot fail to impress upon the mind a most favorable idea of its grandeur and beauty. The dome is most tastefully laid off in compartments, within which the magic pencils of Canova and Pinoli have portrayed allegorical scenes and the busts of eminent Americans, in rich fresco--a style of painting comparatively new in the United States. The floors of the gallery which engird the rotunda, and the winding stairs leading to them, are of iron. By a side entrance on St. Louis street, access is obtained to the second story; the front of which, on this street, is occupied by a suite of ball rooms and their dependencies. The great ball room is magnificent in its size and decorations. The building also has a capacious entrance on Royal street, as a hotel that can accommodate 200 persons. At the corner of Chartres street are the public baths. In the spring of 1840 this building was nearly burnt down--but, in less than two years, it was completely restored to its original splendor. [Illustration] THE COMMERCIAL EXCHANGE This edifice is now being erected upon the south west corner of St. Charles and Perdido streets, fronting one hundred and three feet upon the former, and running one hundred upon the latter. The main part of the building is to be constructed of brick and stuccoed; the upper portion is purely Corinthian the lower entirely Tuscan. The principal entrance on St. Charles street, is by a portico supported by two Ionic pillars, and the same number of pilastres, composed of granite. The vestibule is eleven feet deep, which admits visitors by three separate doors into the exchange saloon, the most spacious apartment of the kind in the United States; it being seventy by one hundred feet, and twenty seven to the ceiling, which is supported by twelve well arranged and substantial pillars. At the rear of this public room are two others, intended for the accommodation of auctioneers, leaving only sufficient space on the left for the necessary offices and access to the second floor.