Some of the sights below (such as Palmyra and the Souq of Aleppo) have been damaged to different degrees due to armed conflict in recent years. It has been reported to me that all these sites are open for visitors.
Syria has plenty of attractions within a small country, but there are two distinctive highlights of visiting Syria. Krak des Chevaliers is the most outstanding Crusader Castle you will ever see. It is far larger and impressive than any of its counterparts. Ensure the weather is good when you visit, because on a cold, windy or rainy day the castle is not that comfortable to visit. Bring good walking shoes as well in order to tread around the many steps and obstacles.
The second highlight is the ancient city of Palmyra situated in the east of the country. Though not as grand as the ruins seen in places such as Turkey the scale of this site is incredible – plan on 2-3 days to comfortably see it all.
Aleppo is my favourite city in Syria, with a wonderful souq that still caters to the local population instead of tourists and the Citadel that towers above the city. This souq catered almost entirely to locals, thus giving it a very different feel to a market targeting tourists.
Bosra in the far south of the country has the best preserved Roman ampitheatre in the world. If you have seen other amphitheatres and tried to imagine what they looked like in their glory days, visiting the one in Bosra will provide your answer.
The capital of Damascus is an incredible city. The area around the enormous souq al-Hamidiyya (and its adjoining souqs including souq Al Bozoreia) is the main area of interest. Nearby to these is the Azem Palace that is a fine example of the wealthy residence. An essential place to visit is the spectacular Umayyad mosque – and it is particularly impressive at dusk. Nearby to this mosque is the burial tomb of the great Salah-ad-Din, the revered Muslin leader who battled against the Crusaders in the 12th century.