Tomb of Cyrus: The World’s Oldest Earthquake Resistant Structure

Natural calamites like floods, hurricanes, and earthquakes have always been considered “acts of god”, yet for centuries our ancestors have refused to bow down to the wrath of the higher beings. Dikes were used to protect homes from floods, and shelters themselves were an act of defiance against the natural elements. Historical and archeological research have revealed that ancient civilizations also had sound knowledge of building earthquake-resistant structures.

The tomb of Cyrus the Great, the founder of the Persian Empire, is believed to be the first structure equipped with base-isolation technology to resist earthquakes. Photo credit: Aleksandar Todorovic/Shutterstock.com

In ancient Crete, for example, many buildings were made of stone blocks connected by wooden elements to introduce flexibility to an otherwise rigid structure, which were prone to cracks when the ground shook. Buildings were also built on top of sand or loose gravel which absorbed vibrations during earthquakes. The Temple of Athena in Troy (1500 BC) rests on a thick foundation of sand, as well as the Doric temples of Paestum (273 BC).

In ancient Greece and Persia, a new technique developed where a different material, like ceramic and clay, was injected between the ground and the foundation so that when the ground shook one layer slid over the other and this minimized damage caused by the shaking. This is known as base isolation, and it is one of the most powerful means of protecting a structure against earthquakes today. In modern buildings, structural engineers use rubber bearings, ball bearings, and spring systems to isolate the structure from the shaking ground.

One of the earliest examples of base isolation can be found in the Tomb of Cyrus in Pasargadae, the capital of the Achaemenid Empire under Cyrus the Great (559–530 BC) in modern-day Iran. Despite having ruled over a vast empire that stretched from the Mediterranean Sea to the Indus River, the Mausoleum of Cyrus the Great is extremely simple and modest. The tomb is roughly cubic in shape measuring a little more than 6 meters by 5 meters. A small doorway leads into the cella. The roof is triangular. The chamber stands on top of a pyramidal base with six large steps. Everything is made of large blocks of stone.

Tomb of Cyrus The Great. Photo credit: Borna_Mirahmadian/Shutterstock.com

The foundation is made of several layers of limestone. The first layer, or the base, is made of stones cemented together with mortar, consisting of a mixture of plaster of lime and ashes or sand, and then smoothed. The upper layers are made of blocks that are tied together with metal bars but not tied to the base. This allows the upper layers to slide on top of the first layer, the foundation, in case of an earthquake.

It’s evident that the Tomb of Cyrus withstood numerous earthquakes for the past 2,500 years, although we are not sure how large those earthquakes were, and whether they were strong enough to trigger the “base isolation” configuration. There are no signs that the blocks and layers had moved, which makes us question whether the system worked and if the tomb builders knew what they were doing and if the pyramidal configuration is actually “base isolation” that protected the building. And here is the funniest part—we are not even sure this tomb is the final resting place of Cyrus the Great.

Illustration of the Tomb of Cyrus the Great by John Ussher, 1865. Photo credit: British Library/Wikimedia

According to the Greek historian Arrian of Nicomedia, who was also the military commander of Alexander the Great, the Macedonian king paid a visit to the tomb after he had looted and destroyed Persepolis. Alexander commanded Aristobulus, one of his warriors, to enter the monument. Inside he found a golden bed, a table set with drinking vessels, a gold coffin, some ornaments studded with precious stones and an inscription on the tomb that said:

Passer-by, I am Cyrus, who gave the Persians an empire, and was king of Asia.
Grudge me not therefore this monument.

There is no archeological evidence that this inscription existed. Even among historians who mention this inscription, there is considerable disagreement to the exact wording of the text. The Tomb was supposedly looted shortly after Alexander’s visit. When Alexander revisited the tomb, he was saddened by its state and ordered the tomb to be restored. If the inscription was destroyed, he surely would have restored it.

The complete absence of the epitaph mentioned in the Greek texts is a mystery, and it does cast doubts on the reliability of the Greek’s account on this detail. So we’ve got a tomb that might not even be of Cyrus the Great, with a sophisticated earthquake-resistant technology that we have no clue if it works.

Only one detailed study of the supposed “base isolation” system in the Mausoleum of Cyrus the Great exists, conducted by the Islamic Azad University of Iran. The author claims that the tomb was simulated in software and subjected to a pretty strong earthquake, before a conclusion was drawn. Unfortunately, the paper is behind a paywall and cannot be accessed.

The Tomb of Cyrus, the Great as on 5 September, 2018 at Pasargadae, Iran. Photo credit: Attila JANDI/Shutterstock.com