1) Diakofto - Kalavryta (rack railway)

- Cave of lakes

Diakofto - Kalavryta Rack Railway:

The Diakofto-Kalavryta Railway is a historic 750 mm (2 ft 5 1⁄2 in) gauge rack railway in Greece. Located on the northern Peloponnese, it runs 22 km from Diakofto through the Vouraikos Gorge and the old Mega Spilaion Monastery and up to Kalavryta, stopping en route at Zachlorou.
The railway climbs from sea level to 720 m in 22.3 km with a maximum gradient of 17.5%. There are three sections with Abt system rack for a total of 3.8 km. Maximum speed is 40 km/h for adhesion sections and 12 km/h for rack sections. There are bridges over Vouraikos River at many locations and numerous tunnels. Passing loops exist at Niamata, Triklia, Zachlorou and Kerpini. Rolling stock sheds and maintenance facilities are located at Diakofto. Additional facilities existed at Kalavrita station during the steam era but they are no longer in use.
The line was to be electrified and EMUs were ordered at Billard, France. Before the cars arrived, the plans for electrification were scrapped, the EMUs were thus not usable when they arrived. As a makeshift solution a power car carrying a diesel generator was placed in the middle of the two cars. This solution has worked very well for decades.
OSE recently completed renovation work on the northern part of the line (major maintenance of bridges, enlargement of tunnels, replacement of the rack and testing of new rolling stock), during which the line was wholly or partly closed. Currently there is a limited service on weekdays with three trains on each direction and an extended service on weekends and public holidays with two additional trains. The trip each way is about an hour. Anyone considering this trip should know that the scenery is spectacular and the new trains are in perfect condition.

For more info about Diakopto - Kalavryta Rack Railway please use this Wikipedia link.

Cave of the Lakes:

In the village of Kastria in Achaia, 9km from Kleitoria and 17km from Kalavryta, lies the famous «Cave of the Lakes». It is a rare creation of Nature. Apart from its labyrinth of corridors, its mysterious galleries and its strange stalactite formations, the «Cave of the Lakes» has something exclusively unique which does not exist in other well-Known caves. Inside the cave, there is a string of cascading lakes forming three different levels that establishes the uniqueness in the world. The cave is an ancient subterranean river bed, whose explored length is 1.980m. In winter when the snow melts, the cave is transformed into a subterranean river with natural waterfalls. In the summer months, part of the cave dries up revealing a lace- work of stone basins and dams of up to 4m. in height. The rest of the cave retains water permanently throughout the year in 13 picturesque lakes. The walls are ornamented with coloured stalactite and stalagmite formation while «chandeliers», «medusas» and «fluted curtains» hang from the high 30m. ceilings. Reflections from the still waters add yet more magic to the scene.
The developed part of the cave is currently 500m. long. It includes artistic lighting. The visitor enters the cave through an artificial tunnel which leads directly to the second floor. The dimensions of the chamber inspire are, rapture, admiration. The lakes are spanned by small, man-made bridges.
Human and animal fossils including a hippopotamus have been found at the cave's lower floor. This part of the cave is intended to become a biological cave laboratory of international standing.

For more info about "Cave of the Lakes" please use this official site.

2) Delphi - Arachova

Delphi:

The site of Delphi is located in upper central Greece, on multiple plateaux/terraces along the slope of Mount Parnassus, and includes the Sanctuary of Apollo, the site of the ancient Oracle. Delphi was thought of by the Greeks as the middle of the entire earth.

Delphi is perhaps best known for its oracle, the Pythia, the sibyl or priestess at the sanctuary dedicated to Apollo. According to Aeschylus in the prologue of the Eumenides, the oracle had origins in prehistoric times and the worship of Gaea, a view echoed by H.W. Parke.

Because Delphi is about 180 km away from Korinthos city, is combinable only with Arachova destination.

For more info about Delphi please use this Wikipedia link.

Arachova:

Arachova is a mountain town and a former municipality in the western part of Boeotia, Greece. It is a tourist destination due to its location in the mountains, its traditions and its proximity to Delphi. Arachova has a panoramic view, uphill small houses and the cobbled streets show a picturesque architecture. The town center includes a huge and steep cliff, the Bell Tower, covered with dense ivy. At the top of the tower is a large 10m height clock. Arachova is famous for its black wine, its "brusque", the colorful textiles, carpets and rugs, handicrafts and woodcut creations as well. The Formaela cheese from Arachova has been designated as a protected designation of origin. Nearby Arachova, modern ski facilities are popular with visitors. Although contemporary culture tends to outdo regional folklore, the town maintains some local customs and demonstrates them at celebrations on 23 April, in the honor of the patron Saint George.

For more info about Arachova please use this official link.

3) Olympia

Olympia is a sanctuary of ancient Greece in Helia on the Peloponnese peninsula, is known for having been the site of the Olympic Games in classical times.

The first Olympic Games were in honor of Zeus.

The sanctuary, consists of an unordered arrangement of various buildings. Enclosed within the temenos (sacred enclosure) are the Temple of Hera, the Temple of Zeus, the Pelopion, and the area of the altar, where the sacrifices were made.

Here you have 3 hours to visit the archaeological site and the museum.

Because Ancient Olympia is about 200 km away from Korinthos city, is not combinable with other destinations.

For more info about Ancient Olympia please use this Wikipedia link.

4) Mystras - Monemvasia

Mystras:

Mystras is situated on the slopes of Taygetos Mountain. The archaeological site stands above the modern village of Mystras and the city of Sparta. Mystras or Mistras  also known as Myzithras, is a fortified town and a former municipality in Laconia, Peloponnese. Situated on Mt. Taygetos, near ancient Sparta, it served as the capital of the Byzantine Despotate of the Morea in the 14th and 15th centuries, experiencing a period of prosperity and cultural flowering. The site remained inhabited throughout the Ottoman period, when it was mistaken by Western travellers for ancient Sparta. In the 1830s, it was abandoned and the new town of Sparti was built, approximately eight kilometres to the east.

For more info about Mystras please use this Wikipedia link.

Monemvasia:

Monemvasia is located on a small island off the east coast of the Peloponnese. The island is linked to the mainland by a short causeway 200m in length. Its area consists mostly of a large plateau some 100 metres above sea level, up to 300 m wide and 1 km long, the site of a powerful medieval fortress. The town walls and many Byzantine churches remain from the medieval period.

Because Mystras and Monemvasia is about 220 km away from Korinthos city, is not combinable with other destinations.

For more info about Monemvasia please use this Wikipedia link.

5) Meteora

The Meteora "middle of the sky", "suspended in the air" or "in the heavens above" etymologically related to "Meteorite" is one of the largest and most important complexes of Greek Orthodox monasteries in Greece, second only to Mount Athos. The six monasteries are built on natural sandstone rock pillars, at the northwestern edge of the Plain of Thessaly near the Pineios river and Pindus Mountains, in central Greece. The nearest town is Kalambaka. The Metéora is included on the UNESCO World Heritage List. Average elevation is 313 metres. Studies suggest that the pinnacles were formed about 60 million years ago during the Paleogene Period. Weathering and earthquakes then shaped them into their present shape. Beside the Pindos Mountains, at the western region of the Thessaly, in the middle of northern Greece, these sandstone rocks rise from the ground. The rocks are composed of a mixture of sandstone and conglomerate. They were formed about 60 million years ago. A series of earth movements pushed the seabed upwards, creating a high plateau and causing many fault lines to appear in the thick layer of sandstone.

For more info about Meteora please use this Wikipedia link