Peloponnese is a region in south Greece. Originally a peninsula connected to the rest of the country by the Isthmus of Corinth, it is now cut off from the mainland by the narrow Corinth Canal, spanned by bridges connecting Peloponnese to Attica across the canal.
It is divided in two administrative parts, the eastern part consisting the Peloponnese Region and the northwestern part, around Patras, partially consisting the Ditiki Ellada Region 
Upon entering through Corinth Isthmos
Loutraki a quiet resort, with very good hotels, a beach and a casino.
Corinth - a nondescript port town. Can serve as a base for Mycenae. Some miles away the ancient Corinth, with the ruins of one of the first civilizations of Greece
Along the north-west route:
Patra - Pretty nondescript city. Main point of arrival for ferries from Italy and Ionian islands.
Kyparissia - A nice town in the centre of Kyparissian Gulf.
Pylos - Very picturesque city in the southwest. Many French-style buildings, as well as a marina and a gloriously shady square.
Methoni - A seaside town south of Pylos. Its main feature is a spectacularly positioned and well preserved castle, which contains both Venetian and Ottoman elements. The town itself is also pleasingly old, and there is a small but delightful beach near the castle.
Koroni - About 30 minutes drive further on from Finikounda is Koroni, a fishing village which snuggles beneath its great Venetian fortress that overlooks the beautiful harbourfront with pavement cafes and fish restaurants with fresh local produce and authentic Greek cuisine. Just before Koroni is the beautiful Zaga unspoilt beach and beyond are many other beaches.
Kalamata - Main city of Messinia Province. Famous for its olives but also a pleasant city with an attractive seafront and stylish new marina.
Nemea, a typical town of the area, hosting interesting ancient and byzantine monuments.
Tripoli - The center of the administrative area, the third biggest.
Sparta - This historic city has a population of 10,000. It has two main arteries which make navigation really easy. To the west of the City is the beautiful, rugged Mt. Taygetos. The Byzantine city of Mystras is a short 15 minute ride away. This has relics worthy of a visit. There is a museum in Sparta housing some artifacts.
Gytheion - A small fishing village. Nice seafood restaurants with plenty of beaches in the area mostly frequented by locals. Nearby Caves of Dyros is a large limestone cave system which is toured on a boat. Here you will find the point where Helen of Troy is said to have started the Trojan War. "The woman who launched a thousand ships."
Along the east route:
Argos — one of the oldest cities of Europe, Argos boasts some ancient ruins including an amphitheater, as well as a medieval castle
Leonidio, a typical well preserved old town of the area
Monemvassia - The Rock of Gibraltar of Greece. Really pretty with an ancient walled city.
Along the west route:
Kalo Nero Kyparissia - Today, the village has developed into a well-organised tourist resort with all the necessary comforts, as taverns, apartments, cafe-bars and nice beaches. Family hotel Irida Resort in Paralia, is a cultural oasis in kalo Nero's most successful tourism resort.
Gialova - An exceptionally pretty fishing village near Pylos in the Southwest. There are a couple of nice hotels to stay in, as well as an excellent campsite. The village also boasts several fine eateries, none of which are too expensive.
Finikounda - A smaller town about 10 minutes drive from Methoni. It is a little more touristy, but does offer wonderful beaches and some nice tavernas.
Along the central route:
Loussios Valey - the craddle of the Greek independence revolution, surrounded by beautiful villages and historic sites.
Mani - the southest tip of continental Europe, one of the most harsh places of Peloponnese during historic times, now hosting many interesting villages, views and beaches.
Along the east route:
Porto Heli, a seaside resort area
You will get along with English pretty well, in the more touristy places you won't have too much problems with German or Italian either. Pick up some Greek, it will be appreciated!
As in whole of Greece, almost all speak from some words to quite fluent English, as it is taught in public schools. Since Greeks travel frequently abroad for education or work and also they love foreign languages, there are many speakers of other languages also, usually French, Italian, German, Russian, some less frequently Spanish.
From Athens, by car or bus; having a car allows occasional stops that are worth along the way to most parts of Peloponnese. Nafplio is a 2hr ride, Sparta about 4hrs, Patras about 2,5, Kalamata about 3 hr 45 mins (3 hrs on the nonstop express bus).
From Athens, by train, using a Proastiakos (suburban) train, running from Athens International Airport all along the north route to Kiato and even Patras through a local train correspondence.
From Piraeus port, through a ferry, to the Saronic islands of Poros or Hydra or Spetses. For accesing the mainland using the same ferry one can get off at the port of Methana or Galatas(through Poros town) or Costa. There are car rental agencies also there.
From Athens International Airport, by plane, to Kalamata. Aegean Airlineslink title operate a daily service.
From Western Greece / Ipeiros to Patras through the Trikoupis bridge (Rio - Antirio).
From / To the port of Patras there many ferries daily from / to Italy
Usually car or KTEL bus.
If timetable is convenient, the train can sometimes offer a comfortable and cheaper alternative. Presently (Jan2011) cancelled for all lines, except for the north line Athens to Kiato to Patras.
Ancient Corinth. The relics of the famous town where St Paul lived and teached for quite some time. Nearby is the castle of Acrocorinthos and the opposing Penteskoyfi.
Ancient Olympia: The first olympic games were in Olympia in honor of Zeus.
Mycenae : From the hill on which the palace was located one can see across the Argolid to the Saronic Gulf.
Epidaurus - Ancient theatre : A small city (polis) in ancient Greece, at the Saronic Gulf. One of the greatest ancient theatres in the world.
Nafplio It is a beautiful seaport town in the Peloponnese in Greece.