A visit to Corinth makes a nice day tour from Athens. To go to Corinth from Athens by train, take the metro blue line from Syntagma all the way to the last station on the line-D. Plakentias. Metro cost €1.4 per person one way. The blue line is the same train line that goes to the airport from the city.
Transfer to one of the suburban trains from D. Plakentias bound for Aktio. Corinth is third to the last station and it takes one hour from D. Plakentias to Corinth station. You may buy the train ticket at the station, the cost is €14 per person round trip. Be sure to validate the ticket before boarding and keep the validated ticket with you at all times as inspectors would ask for your ticket at some point in the journey.
Ancient Corinth is about 5km away from the Corinth train station. To go to Ancient Corinth we took a taxi from the station and it cost €10 each way.
Ancient Corinth ruins include a temple to Apollo and a Roman Fora. If you are Christian this place is significant as one of the places where Saint Paul established early churches and the Roman Fora is where he was tried by Gallus after Jewish accusations that he was preaching a foreign religion. Entrance fee to the archaeological site cost €4. They close at 3pm.
On the top of the mountain is Acrocorinth or the Acropolis of Corinth. You can drive here or hire a taxi to see amazing views of the Agean Sea.
Aside from Ancient Corinth ruins, visitors could also see the Corinth Canal but this attraction is closed in winter.