The life of Oleksandr Mykolaiovych Karasiov, a well-known archaeologist, a specialist in antiquity of the Northern Black Sea region, the discoverer of the Olbian agora, stoa, gymnasium and the central temenos of Olbia, was eventful. His biography and the path to archaeology was very thorny and difficult. However, until now the biography of this researcher has not been given enough attention, which is corrected by this article. Oleksandr Karasiov was born in St. Petersburg on August 3, 1902. During his busy life, before becoming an archaeologist, he managed to work as an extra in the health department at the registry office, volunteered in the Baltic Fleet as a journalist, began studying at the Higher School of Pilot-Observers and entered the Institute of Civil Engineers at the Faculty of Architecture. And this is not a complete list. Finally, in January 1925, he entered the Leningrad State University at the Faculty of Linguistics and Material Culture. Since 1926, during his studying at the university, O. Karasiov participated annually in the archaeological excavations at Olbia, which were initially led by B. V. Farmakovskyi, and considered himself as one of his disciples. Since that time, O. Karasiov was a tireless researcher of Olbia for 45 years, includingt 34 field seasons. The greatest archaeological achievements of O. Karasiov were made after the Second World War, when he, together with his wife, O. I. Levi, led the excavations at the «E» site, where for the first time they made the most significant discoveries published in the work Olvia. Temenos and agora and in many other articles. O. M. Karasiov owns the longest list of works on the monumental buildings of the Olbian temenos with a detailed examination of cultural stratifications, a functional definition of various types and purposes of stone structures, among which the most significant are the largest altar in the Northern Black Sea region, the temples of Apollo Delphinius, the spherical foundations of a possible Delphinion and the temple of Zeus of the Hellenistic time, large and small stoas, sacred treasury, etc. A thorough study of the monuments of the Olbian temenos, representing a single architectural ensemble and their publication, rightfully belongs to one of the most important archaeological discoveries made in Olbia and in the Northern Black Sea region in general.