The terminal stations in the city should be either above or below the street levels. They should be centrally located, but always arranged so as to avoid the closing of streets. The two best available locations for permanent passenger stations for all the roads are, first, between Canal and Clinton streets from Lake Street to Twelfth Street, and on Twelfth Street widened as proposed. In the case of the terminal stations between Canal and Clinton streets, the tracks either under or over street grades may be allowed to extend out to the street curb lines and possibly farther. Whether under or over the grade, the railroads should be allowed to occupy this entire space. In case the overhead system be adopted, there should be two open plazas, one preferably at Washington Street and the other at Congress Street; and the plazas should have no tracks above them, except passovers on each side of the plazas. [Illustration: LXXVI. DRESDEN. VIADUCT AND RAILWAY STATION (HAUPT BAHN-HOF) PASSING ABOVE THE NORMAL STREET LEVEL, ILLUSTRATING THE TYPE PROPOSED IN THE OVERHEAD SCHEME FOR RAILWAY STATIONS WEST OF THE RIVER.] In case of overhead installation, the roads may, for the present, burn coal in their locomotives. In case of depressed rights-of-way coal cannot be burned unless the spaces from street to street over the railways be kept open. In the long run, it will be very costly to do this, because all this space from street to street, so long as not needed by the railroads, could be used for markets, commercial booths, and warehouses, the rentals reducing the cost of operation to the road. [Illustration: LXXVII. VIENNA. A RAILWAY VIADUCT PASSING OVER AN IMPORTANT STREET.] In case of elevation, the viaducts over the streets should have sidewalk lights between the rails, and these viaducts should be freed of posts, deep girders being used; the walls and pavements should be as nearly white as possible. The Eighth Street subway under the Union Station yard at Washington, D.C., is a good example of what such a structure should be. There is no reason why these viaducts should not be very attractive when brilliantly lighted. Each should have a handsome police house in the center, with windows arranged to give a clear view of the entire space included under the tracks. There is no reason why this construction, even if elevated, should not present a very pleasing appearance as seen from Canal Street or Clinton Street. Whether there are buildings or only unoccupied spaces beneath, they can be enclosed by masonry walls extending high enough above track level effectually to screen the trains from view. Such a structure would be similar in general effect to the great Roman aqueducts. It might be made not only of practical value, but at the same time a highly interesting and even a grand architectural detail lending orderly distinction to that part of the city.