As you wander up the library street (it will be on your left hand) at the ruins corner follow it around to the left and soon, after some more winding, you will reach The Roman Agora and the Tower of the Winds also known as the Holorologikon of Andronicus. This latter was for many years thought to be a water clock but local archeologists are today calling it the bath house of the winds for some reason.
The Romans (obviously) built this commercial market place and it was funded by Julius Caesar himself in 51 AD but not completed until the reign of Augustus. This newer Roman agora gradually supplanted the Greek agora to the east. Today the area has returned to being a commercial one but for many years the ruins themselves were covered over with dwellings all of which have been removed to uncover Athens' glorious classical past. As you approach the Agora on you left you'll see a remnant of Athens' Turkish occupation the entrance to the wheat bazaar below.