Palmyra, a three-hour ride from Damascus, has some of the most famous remnants of the Classical Period in the Middle East. Set in an oasis, Palmyra was ruled by the legendary queen Zenobia, who had the gall to stand up against the might of the two great empires of the Romans and the Persians. She ultimately fell to Roman King Aurelian who took her captive and destroyed the city of Palmyra in 272 AD. The ruins of the Valley of Tombs, the Hypogeum of the Three Brothers, the Temple of Baal and the Monumental Arch are some of the sights to see.
Aleppo is the second largest city in Syria, and for those who are traveling overland from Turkey, this is usually the first stop over point and is great to stay for a couple days. The one landmark in the city is the Citadel, which must not be passed up. This 12th century fort, which sits up on a hill and surrounded by a moat is now mostly in ruins. Exploring the chambers, dungeons and labyrinths will make feel like you're on an adventure. Well connected to Damascus by road, it is 350km away.
Bosra used to be an important ancient Roman city, situated between two wadis (valleys). In ancient days it was an important stop along trade and pilgrimage routes. Its ruins of Roman structures and the present day modern structures of black basalt rock provide a contrast. There is a well-preserved 15,000 seat Roman amphitheatre and the surrounding citadel, the Roman baths, a mosque, monastery and cathedral that you must visit. In October, a Folklore and Music Festival is held here. You can either drive or take a day trip from Damascus, or visit it from Der’a, where you could spend the night. Buses run from Damascus as well as Der’a to Bosra. There is a luxury hotel, and budget rooms in the citadel.