This is a small structure adjacent to the theater and located next to the monumental gate. It was built on a podium having a height of 1 m.
In front of it there is a pool. It is a fascinating monument with a round niche in its front side and two projecting parts on its both sides, each having two full and two half Korinth style columns. The arch of the central niche has an opening of 7m and is 15m high. Both inside the central niche there were statues and the columned sections on the sides.