In 1981, Grigorios Longos created in collaboration with Grigorios Karatzavelos the “Loggos & Associates Technical Office”. Two years later Vassilios Tsivos joined the team. The three of them as a team led the office to the development of major historical studies (Goulandris Museum, Katrakeio Theater, Arsakeio of Ioannina among others) and is considered one of the most recognized firms of the field

Mr. Longos was born in Naoussa in 1945, graduated in 1971 from the Technical University of Munich as Aeronautical and Mechanical Engineer and then worked in the distinguished construction company Frank Basil S.A. Mr. Karatzavelos was born in Lamia in 1929, graduated in 1951 from Mechanical Engineering School and was one of the founding members of Frank Basil S.A. in 1958. Mr. Tsivos was born in 1954 in Athens and graduated in 1977 from the National Technical University of Athens as Electrical and Mechanical Engineer. He worked as an assistant of Professor Papageorgiou head of the Section of The Thermal Engineering, Laboratory of Steam Boilers and Thermal Plants. Mr. Tsivos is a senior executive of PPC S.A. – HEDNO S.A.