For some time I was confused about Odessos, because I just assumed it was the same as Odessa, Ukraine. However, it isn’t. The modern day city is Varna, which is the third largest city in Bulgaria.
Of course, in ancient times this was Thrace, and the Odrysian kings either ruled or made alliances with Odessa at various points. The parts of Thrace not already under the control of Philip II were conquered by Alexander the Great, and Odessos came with them.
Later on, the area was overrun by Celts. Although there has been a lot of archeology done on Odessos, today we don’t know as much about its history as with other similar-sized cities elsewhere in Greece, primarily because the Greeks considered them barbarians.