Achaemenid kings started building the palatial complex of Persepolis in 520 BC. The archaeological site reflects the former glory of the imperial capital of ancient Persia. Alexander the Great ended the rule of the Achaemenids in 330 BC by invading Persepolis and burning it down. Impressive ruins of the palaces, mausoleums, columns and reliefs can nevertheless still be admired to this day.

King Untash-Napirisha, ruler of the Kingdom of Elam, built Tchogha Zanbil in the 13th century B.C. With the Elamites in constant struggle with the neighboring powers of Mesopotamia, the royal city was extremely well fortified. In the center are the remains of the oldest religious building in Iran. The gigantic temple tower was once 52 meters (171 feet) high and had five floors.

Located 90 kilometers to the northeast of the city of Shiraz, Pasargadae was the earliest capital of the Persian Empire under the Achaemenids and was founded by King Cyrus II in the 6th century BC. The city had a sophisticated underground irrigation system. Prehistoric monuments were also found next to the site. The picture shows the tomb of Cyrus II.

Also known as the "Black Church," the former Armenian monastery is located in the Iranian province of West Azerbaijan. Armenian Christians believe that the church dedicated to Judas Thaddaeus was first built there in 68 AD. After being damaged by an earthquake, the structure was rebuilt in the 14th century. It is still a place of pilgrimage for Armenians from Iran and neighboring countries.

Tabriz, on the historic Silk Road, has long been one of the most important cities in Persia, the home not only of a bazaar but also of religious and educational institutions. The world's largest covered bazaar had its heyday in the 13th century when Tabriz was the capital of the Safavid Empire. The Safavids later ruled throughout Persia and established Shiite Islam as the state religion.

A poet and mystic, Sheikh Safi al-Din was the namesake of the Safavid dynasty. The architectural complex named after him, a UNESCO World Heritage Site since 2010, includes a onetime Sufi center and the sheikh's tomb. As the founder of this first Sufi religious complex in the Ardabil region, Safi al-Din lived there with his family. It later became a sacred place for the Safavids.

Located the geographic center of modern-day Iran, the city of Yazd was established in an oasis between the Kawir salt desert and the Lut desert. A center of Zoroastrian religion, it is renowned for its fire temples. A special system of water channels and pipes, known as qanat technology, was created to supply water, and wind towers were built for cooling.

Fire is the most important of the four Zoroastrian elements, and fire temples are a central location of worship. Zoroastrians do not use them as a prayer house in the classic sense though, but instead as a space for meetings and exchanges, devotions and memories. Yazd is the heart of the Zoroastrian religion, which had its heyday between the 2nd and 7th centuries AD.

Eram Garden is an impressive example of the historic Persian gardens first built in the Middle Ages. Surrounded by high walls, they usually include a water channel and a summer palace. An important part of Persian culture, the gardens embodied the idea of earthly paradise — the word itself is actually derived from the ancient Persian term for garden, "Paradaidha."

One of 11 bridges over the Zayandeh River, the Si-o-se-pol has 33 arches. The two-story viaduct was built in the Safavid period in the early 16th century. Covered arcades enclose the main traffic route on both sides, and wide stairs lead to the promenades along the bridge. In roofed tea houses one can drink tea and smoke a waterpipe.

Dating from the end of the 18th century, the onetime Qajar government palace was the official seat of the Persian monarch before the Islamic Revolution in 1797. Between 1925 and 1945, a large part of the palace was demolished to make room for new buildings. Today the palace houses a museum displaying ancient ceramics, jewelry and weapons.

The 45-meter-high (148-foot-high) Azadi Tower ("Freedom Tower") is the symbol of modern Tehran. Formerly called Shahyad Tower ("Memorial of the Shahs"), it was built between 1969 and 1971 to mark the 2,500th anniversary of the foundation of the Imperial State of Iran. The tower is covered with over 25,000 white marble stones and is a link between Islamic and Sassanid architectural style.

What is now left of the ancient ruins at Palmyra - known as the "Pearl of the Desert" - is uncertain after a new strike by IS militants on Thursday. This photo shows the face of statue at a destroyed museum in March 2016. Syrian government forces had recaptured Palmyra that month from jihadists, who view the UNESCO-listed site's ancient ruins as idolatrous.

This image of Palmyra's Tetrapylon was taken in 2014. If SANA agency reports are correct, this monument is no longer standing. Current images after Thursday's reported strike are still unavailable.

This image shows the Roman amphitheater, which was originally built around 200 A.D., in April 2016. Reports now say the facade has been destroyed by IS extremists. In 2015, jihadists used the site - which once premiered plays - for mass executions. After the city was retaken from IS last year, the Russian government staged a classical music concert here to celebrate the success.

Palmyra's National Museum, shown here, also suffered heavy losses under IS rule. Its treasures were looted, some were damaged and others burned.

This picture, taken last March, shows the ruins of Palmyra's Temple of Baalshamin - just two columns left standing after IS destruction the year before. The smaller image, held by the photographer, shows the image he took in 2014 - with clearly more in the background behind the columns.