Historical castles usually occupy the best strategic spots in the landscape. And strategic sites, it turns out, have a lot in common with elements that make for some of the best photography spots. A 3,000-year-old historical military complex in southeastern Turkey's Diyarbakır and its archaeological ruins don't serve the military anymore but offer a superb opportunity to take some great photographs.

The Zerzevan Castle has been the subject of some unique and mesmerizing photographs against the backdrop of the sun setting beyond the horizon, recently. Built as a military settlement during the Roman Empire period, the complex stands at an elevation of 124 meters (406 feet) in the beautiful landscape of Diyarbakır.

The site, which was added to the UNESCO World Heritage Tentative List last year, has also been hosting archaeological excavations since 2014, most recently unearthing the 1,800-year-old entrance to the castle.

The castle's location used to be a strategic point between the ancient cities of Amida, Dara, Edessa and Nisibis. It was also located along "The Royal Road," which was a trading and military route with significant importance.

It was the Roman Empire's easternmost border point, and witnessed massive struggles between the two great powers of the time, namely the Romans and the Sassanids, according to the UNESCO listing.

The architectural remains uncovered at the site include observation and defensive towers, churches, houses, cisterns and other historical structures.

There is also the necropolis area, which is a large cemetery with elaborate tomb monuments with "necropolis," literally meaning "city of the dead."

The most important structure unearthed at the Zerzevan Castle has been the Mithraeum, a temple of Mithraism, also known as the Mithraic mysteries, which was a Roman mystery religion centered on the god Mithras.

The underground temple and a subterranean sanctuary were constructed by carving into a rock and in its day were able to hold 400 people.

The historical inscriptions and symbols at the entrance of the structure still stand visible today.

Numerous sacrificial artifacts remain in the temple, like carved bull blood bowls and pools, and points to religious ceremonies in which animals were sacrificed, mostly bulls, in Mithras rituals.

The castle saw restorative works during the fifth-century Eastern Roman emperor Anastasios I and the sixth-century Byzantine emperor Justinian I.

The settlement is believed to have been used until 639, when it was conquered by Islamic forces.