Thessaloniki Transport Authority

The Thessaloniki Transport Authority (Greek: Οργανισμός Συγκοινωνιακού Έργου Θεσσαλονίκης, 'Thessaloniki Transport Project Organisation', abbreviated as ΟΣΕΘ), is an anonymous company which plans, coordinates, and oversees the urban transportation network of Thessaloniki, the second largest city in Greece. It is abbreviated as TheTA in English, a wordplay on the letter Theta which the first letter the word "Thessaloniki" in Greek.

Source: Wikipedia — Thessaloniki Transport Authority (CC BY-SA 4.0)