History about Thira - Santorini
Two million years ago, the present island of Thira was three  islands or rocks. Through many volcanic eruptions over the years, lava filled the gaps and connected the three islands/ rocks forming a circular island with a crater in the middle of 3000 feet high.
In ancient times the island of Thira was called "Strongili", which means Round Island. After the first eruption of the volcano, that resulted in the island's present shape, Thira was named "Kallisti", meaning the Fairest One. During the 10th Century B.C., the Dorians invaded the island and settled seven villages. They named it Thira, after their ruler from Sparta.  Then, in the 13th and 16th centuries, Venecian crusaders named the island Santorini, after the island's patron, Saint Irene, who died here in 304 A.D. While occupied for three centuries by Turks, until 1832, the island was known as Denmemezlic. 
The island is near the joint of two tectonically plates. It is when these two plates move that we have earthquakes and eruptions.   The eruption in 1625 B.C. caused the island to remain uninhabited for 300 years and the destruction of the Minoan Civilization. A 200 meter high tidal wave (tsunami) from the volcano of Thira reached the coast of CRETE. The blast was heard in the Scandinavian  countries and Asia Minor and volcanic ash was found in California, Greenland and Ireland. Many earthquakes followed that same year, which caused the 3000 feet crater to collapse inwards and break the central and western parts of the island in 5 different pieces allowing water to fill in and create the present day Caldera. Approximately 83 sq. kilometers of land disappeared. 
Present day Thira is the largest island with 72 sq. kilometers of land.  The four other islands are, Thirasia with 350 inhabitants; New Burned Island, Old Burned Island and the White Island.
Thira has about 10,000 inhabitants and 13 villages.  There are over 550 churches on the island, even though they say there are only 365,  one for each day of the year. By the way, in Thira we still register the donkeys the same way we register the cars.
The highest point of the island,  Profitis Ilias, is 565m high. On the top of this mountain there is a monastery built in 1771. Currently, five monks live there. Pyrgos, one of the most traditional villages on the island, is on  a small hill next to Profitis Ilias. Virtually untouched by tourism, the village is famous for the ruins of a Venetian  Castle, that was built in the 13th century. There is an old saying: Pyrgos has more churches than houses, more wine than water and more donkeys than men . 
The legend of Atlantis is associated with the island of Thira. This is because Plato writes about an island, with a very advanced civilization, that disappeared under the sea.  Thira was also believed to have had a very advanced civilization and most of the island disappeared under the sea. Fira is the capital of the island, located 1000 feet above sea level. The view from Fira is fantastic. Beautiful white-washed buildings are scattered along the cliff top adorned with turquoise blue door frames.  Jewelry, clothing, souvenirs, pottery shops and art galleries line the narrow winding paths. There are also many cafe bars looking over the Caldera and restaurants.
During the 13th Century there was a Venetian occupation on the island. The Venetians fortified 5 different places on the island with Imerovigli as the capital. They chose Imerovigli because it is the highest point of the Caldera. There is also a strange rock formation in the front of the village, called Skaros. Here is where they built their strongest of the five castles. The castle was destroyed in 1956 during a terrible earthquake that registered 7.8 on the Richter scale.  
Oia: A little town with white-washed houses, located at the northern edge of the island. Until World War II, Oia was the economic center of the island. Today, it is not as commercial as Fira. It is rather a graphic paradise for people who love photo shooting and video recording. There is  lots of galleries of modern art and traditional crafts. Oia can be reached by bus, with a fare of about 75 cents, or by taxi, for $25, from Fira. Oia is the most popular place on the island to witness an amazing sunset.
Years ago, the main income of the islanders was the exportation of  pumice stone. Two million tons of pumice was exported per year. The insulation of Suez Canal was made out of Thira's pumice stone mixed with cement. Produce included the  tomato paste  made from the local cherry tomatoes, fava beans and the famous Thira wine. However, tourism has become the main source of income for all islanders for the last thirty years. According to statistics, there are 75 domestic and 85 charter flights arriving to Santorini per week, during summer time. There are many beaches on the island. Most famous are Kamari, Perissa, Perivolos, Monolithos, Amoudi and Baxedes. 
Prehistoric Akrotiri: This area is considered to be 4,000 years old. The first excavation began in 1869, but not a lot of work was done until 1969 when archaeologist Professor Marinatos, resumed work. Today, excavations have uncovered an area of over 10,000 square meters and there still remains a lot more to be discovered. The quality of frescoes, the pottery and the magnificence of the buildings testify to an important community that existed many years ago.