Visit to the Ancient Agora (Forum)
As you leave the Acropolis, the rocky hill ahead on the left is the Areopagus. Enter through the little gate just to the right of the Areopagus and walk straight down through the Eleusinion to the Ancient Agora. Admission is included in the ticket from the Acropolis.
The benches just past the ticket office on the left make a good meeting point / picnic spot.
The Ancient Agora is quite extensive and can easily take an hour or more to explore, but if you continue straight along the Panathenaic Way it’s a five-minute walk to the exit gate. The street running next to the perimeter of the Ancient Agora is Adrianou, one of the main streets running up through the Plaka, and is lined with restaurants and cafes.
Down to the left, a two-minute walk brings you to Thisseo metro station, and the path continuing beyond the station leads to the Kerameikos Archaeological site (also included in the ticket from the Acropolis).