At this important junction and crossing of the aqueducts the Marcian arcade originally made one of the usual angles. The more lofty arcade of the Claudia and Anio Novus was then carried over it, with the Anio Vetus half underground, nearly on the same line; and the modern aqueduct, called the Felice, is here carried against and partly upon the old Marcian arcade. The medieval architects took advantage of this crossing to build a tall tower upon it; the five conduits or _specus_ can be seen inside the tower, and half arches abutting against it in a very picturesque manner, all of which are shewn in the Section in the upper part of the plate, and in the Photo engravings. The Plan in the lower part of the plate shews the arrangement, and also the small river Almo, now called the Marrana, winding round it. PLATE X. [Illustration: X. THE AQUEDUCTS.—CLAUDIA AND ANIO NOVUS. ENTERING ROME IN A TOWER OF THE SESSORIUM. A. SECTION. B. PLAN, OF THE PISCINA MADE IN THE TOWER.] Piscina of the Anio Novus at the entrance into Rome, in a tower of the Wall of Aurelian, and of the gardens of the Sessorian Palace, now of S. Croce in Gerusalemme. A. The Section. B. The Plan. By a singular coincidence it happens that the inner wall of this tower has been destroyed, so that the whole of the interior is displayed, and shews exactly what an ancient piscina was. The water comes into the right-hand upper chamber, it then descends into the chamber under it, as is marked by the arrow in the drawing, it then passes through small holes in the partition wall into the left-hand lower chamber. [The artist has represented a _large_ opening through this wall, but this must be a mistake, owing to the wall being partially broken away; there are always _small_ holes through this partition wall.] The space between this tower and the corner of the wall in the Sessorian gardens, where it turns sharp to the west, was a large reservoir, or Castellum Aquæ, for the Claudia; it is not at a sufficiently high level for the Anio Novus. PLATE XI. THE AQUEDUCTS AT THE PORTA MAGGIORE AND THE PORTA TIBURTINA. [Illustration: XI. THE AQUEDUCTS.—AT THE PORTA TIBURTINA. A. MARCIA, TEPULA, JULIA, AND FELICE. THE AQUEDUCTS.—AT THE PORTA MAGGIORE. B. MARCIA, TEPULA, JULIA, AND FELICE; CLAUDIA AND ANIO NOVUS CROSSING OVER THEM.]