This part of the World Heritage site in the ancient city of Palmyra in Syria no longer exists: "Islamic State" militants have blown up the 2,000-year-old temple of Baal Shamin. The inner area of the temple and the columns collapsed through the explosion. The rest of the ancient city remains strongly at risk.

The ruins of Palmyra lie right in the middle of the Syrian desert. The once prosperous metropolis was surrounded by palms - hence its name - and for centuries was a stop for caravans traveling to the Silk Road. The settlement was a center of wealth and trade. But, gradually, the golden age faded, and sand blew over the city. The ruins were later excavated, and given World Heritage status in 1980.

In the 1st century AD, the Palmyrenes built a grand Roman-style temple for the deity Baal. It formed the center of religious life in Palmyra, which joined the Roman Empire under Emperor Tiberius some time after 14 AD. It is scarred with bullet holes - stark reminders of the ongoing Syrian civil war.

Created in the 2nd century, the Great Colonnade stretches on for more than a kilometer (0.6 miles). Spices, perfumes, precious stones and other treasures once passed down this magnificent colonnaded boulevard. The avenue's entrance is marked by Hadrian's Arch, built in honor of the Roman Emperor Hadrian. It's a fine example of the Greco-Roman style, extremely popular at the time.

The Tetrapylon of Palmyra was built on a crossroads. The four groups of slender pillars, each supporting an alcove, were made of red granite brought in from the quarries of Aswan. Each one used to house statues. Today, almost all the columns are replicas. Only one is an original.

Palmyra bore many characteristics of a Greco-Roman city. It had a portico, thermal baths and an amphitheater. Many oriental dramas were performed on this stage. Unfortunately, the plays, written in Aramaic, haven't survived. In addition to being a theater, the arena was also used for battles between gladiators and animals.

Some 200 statues of important individuals once stood here, taking up honored positions in the porticoes of the agora, or main square. In the agora's southwestern corner the remains of a building where the city council likely held its meetings can be seen. The council was made up of representatives from influential merchant families, responsible for shaping the fortunes of the desert city.

There are a number of burial grounds just outside the city gates. Large families built tall towers housing ornate sarcophagi and tombs big enough for several generations. There are also many underground gravesites decorated with rich architectural flourishes and frescoes that hint at the daily life and wealth of that period.

In 300 AD, Palmyra became a military base, and came under the power of a string of different rulers. The golden age faded, and the city's splendor was covered up by the desert sand. The city's ruins survived the civil war raging in the country since 2011, but now, the ancient city is under threat from "Islamic State" militants, and UNESCO fears it could face a tragic fate.