A couple of key thoroughfares cross the city, including the one connecting Sofia with Istanbul through Edirne, as well as the one between Sofia and Burgas through Stara Zagora. Plovdiv is regarded as the gate to the Rhodopes, as most people who head for the mountains choose it as their starting point. The city has three train stations (and an additional railway stop) and three bus stations. There are two types of buses that run in Plovdiv.
Plovdiv is possibly known at the time as a Thracian fortified settlement named Eumolpias according to Ammianus Marcellinus, in 342 BC it was conquered by Philip II of Macedon, father of Alexander the Great, who renamed it Philippopolis ("the city of Philip"), rendered in Latin as Philippopolis, in his own honour. It later became independent under the Thracians, until it was incorporated into the Roman Empire, under which it was also called Trimontium (City of Three Hills) and served as metropolis of the province of Thrace. Thrimontium was an important crossroad for the Roman Empire and was called "The largest and most beautiful of all cuities" by Lucian. Via Militaris, the most important military road in the Balkans, passed through the city. In what was one of the most glorious periods in the history of the city, it spread beyond the three hills, and numerous public buildings, shrines, baths, and theatres were built.
More about Plovdiv from Wikipedia