Thessaloniki, or Salonica, was an important city on the Roman road Via Egnatia (which, incidentally, is still the city's main street in 2004) between Rome and Constantinople.

This is the remnant of a triumphal arch built by the emperor Galerius to commemorate his victory over the Persians in AD 305.

(I had no idea the Romans made bricks.)

This is called the Rotonda. It was built in the 300s as part of Galerius's palace, but it was turned into a church by Constantine the Great. Under the Ottomans, it became a mosque. (More bricks.)

The rest of these pictures show the remains of the Roman forum. Apparently, excavations were only begun in the 1970s.

This part is now used again as an open-air theater.