3/37.- Palmyra, the Tetrapylon
Most hotels in Tadmur are located close enough to the ruins of Plamyra to walk. The best time to visit the ruins is early in the morning or late in the afternoon, specially during the hot summer months. You can visit the ruins on your own, or hire a guide (ask your hotel for info on guided tours.)
In the picture you have the Tetrapylon, which sits at the intersection of the two main roads in the old Roman city, the Cardo Maximus and the Decumanus Maximus.