Constantine Karatheodoris was of the greats of mathematics who had an international reputation. His scientific investigations extended beyond mathematics to include physics, history, and archaeology.

Constantine was born on September 13, 1873, in Berlin. His father Stefanos Karatheodori served as Ottoman Ambassador in Brussels, St. Petersburg, and Berlin. His mother Despina Petrokokkino came from a noble family of Chios. Unfortunately, the young Constantine and his sister lost their mother at the age of 28 who died "of pneumonia in Cannes" in 1879. Both children were raised by their grandmother.

From 1891-95, Constantine studied civil engineering at the military college in Brussels. Upon graduating, he accepted an invitation from his uncle Alexandros Karatheodoris Pasha, the Governor-General of Crete (1895-96), to visit him in Chania. It was here he met the future Greek prime minister, Eleftherios Venizelos, with whom he would establish a long life friendship.

He then went to Mitylene assisting his cousin Ioannis Aristarchus with road work construction during the period 1895-97. In 1898, Constantine went to Egypt to work as an engineer for a British company involved in the construction of the Aswan Dam. During his stay there, he continued to study mathematical textbooks, and also made measurements at the main entrance of the pyramid of Cheops and he published his findings in 1901.

In Egypt, he realized how much charm and influence mathematics had on him and realized that the job of an engineer didn't satisfy his restless spirit. He became acquainted with his mother's relatives in Alexandria and became known to the local Greek community there. Constantine wrote a book covering Egypt's history, culture, military, political, geography, and the achievements of the Greek community. 

So in 1900, he surprised his family by leaving his engineering job to study mathematics in Germany. In the next two years, he attended mathematics classes at the University of Berlin with eminent professors such as Lazarus Fuchs and Ferdinand Frobenius. In 1904, he submitted his doctoral dissertation titled On Discontinuous Solutions to the Calculus of Change at the University of Gottingen, which was accepted and in 1905 was conferred with a doctorate in Philosophy of Mathematics.

In February 1909, Constantine married his distant relative Efrosini Petrocochinos and had two children: Stefano and Despina. Both children only spoke Greek at home and ensured that they maintained their Greek customs and Orthodoxy growing up in Germany.

The fame he gained in the following years in Germany brought him into friendly and professional contact with Albert Einstein. The two men met in 1915 maintained a scientific relationship based on mutual respect. Einstein praised Caratheodoris' scientific work. Some of their correspondence is housed in the national archives of Israel.

Caratheodoris was appointed professor of mathematics at the University of Gottingen in 1913, a position he held until 1918. At the end of the war, he went to Berlin and remained there until the end of 1919.

He submitted a memorandum written in French outlining his ideas for the establishment of a new university to the Greek government in 1919. Whilst he recognized the importance of Athens as the center of Hellenism, it was important to consider a decentralized system to take into account the Greek communities that lived outside the Hellenic Kingdom. Ionian University would fulfill that role by linking the Greek world with the Orient.

A wealthy Greek named Stavros Palatzis living in Paris would provide the financial backing for the construction of the university buildings and would cover the daily expenses of the university which would be paid "in two installments each year." On March 20, 1920, Venizelos, Leonidas Paraskevopoulos, the commander-in-chief of the Greek army in Asia Minor, Apostolos Psaltof, a respected doctor in Smyrna, and Caratheodoris met on the battleship Falcon (Ierax) anchored in Smyrna harbor to discuss how this institution would be administered.

In 1920, at the invitation of Venizelos, he undertook to organize the newly established Ionian University in Smyrna. The university was established under Law 2251 of July 14, 1920 "Concerning the Foundation and Operation of a Greek University in Smyrna" published in the Government Gazette. A discussion took place with Venizelos, Aristidis Sterghiadis, the Greek High Commissioner, and Caratheodoris on a battleship in Smyrna harbor in August 1920 to implement this law. Caratheodoris wanted to make it into an excellent institution of higher learning where students would receive an outstanding education. He remained in Smyrna until the collapse of the Asia Minor front in September 1922.

When the Turks were about to occupy Smyrna, he managed to save the library and many of the laboratory instruments of the Ionian University and transferred them to the University of Athens. He stayed in Athens in 1922 and was appointed professor at the University of Athens and in the following year at the National Technical University of Athens.

Disappointed with the state of Greek universities, he left Greece in 1924 to become a professor at the University of Munich, which at the time was the second-largest higher education institution in Germany and staffed by eminent professors. In 1928-29, he was a visiting professor at Harvard, University of Texas (Austin), Stanford, and Berkeley.

In 1930, again at the invitation of Eleftherios Venizelos, he took over the duties of government commissioner to reorganize the established university of Athens and the newly formed one in Thessaloniki. His proposed reforms were blocked by conservative forces within politics and academia to maintain the status quo. Caratheodoris was unhappy with these groups blocking his attempts to modernize Greece's university system.

In 1932, he returned to Munich and remained in that city, even during the difficult years of World War II. It is difficult to pinpoint why the Nazis never imprisoned him for his links with Jewish colleagues; he seems to have kept his opposition to Nazism to himself. 

His contribution to mathematics was especially important in the fields of real analysis, functional analysis, the theory of measure and integration, and thermodynamics. He spoke and wrote in Greek, French, English, Italian, and ancient languages.

Caratheodori died in Munich on February 2, 1950, at the age of 77, and was buried in the Waldfrinof cemetery in the Bavarian capital. The title of Caratheodoris as a ‘Greek genius’ is well deserved.