Parker, John Henry: The archaeology of Rome (4): The Egyptian obelisks to which is added a supplement to the first three parts, which form the fist volume (Oxford, 1876)

The Egyptian Obelisks.

Description of Plate II.
THE OBELISK IN MONTE CITORIO.
This bears the name of Psammeticus, and was executed in Egypt
by Psammeticus II., b.c. 594—588. It was brought to Rome by
Augustus, after the reduction of Egypt, and the deaths of Antony
and Cleopatra, b.c. 30, and was first set up near the present
church of S. Lorenzo in Lucina, to serve as the gnomon or pointer
to throw the shadow on the great sun-dial, which Augustus made
there for a sort of town-clock. It was not removed to Monte
Citorio until a comparatively recent period. (See p. 4.)