Giant Fortress Found Beneath Mega-monument From Time of Alexander the Great

An enormous fortress wall has been discovered hidden underneath an ancient burial mound from over two thousand years ago.

Archaeologists in Cyprus found the rampart, part of a fortress defensive wall, as they were excavating the burial mound.

The mound itself measures 328 feet long by 196 feet wide, and is thought to have been constructed in the third century B.C.E., during the era of Alexander the Great, according to a statement from the Cyprus Department of Antiquities.

The newly uncovered rampart hidden within the mound is thought to have been built even earlier, dating back to the fifth century B.C.E.

The large mound, called the Tumulus of Laona, has been undergoing excavation for nearly ten years. It is less than a mile to the east of the sanctuary of Aphrodite.

Stock image of an archaeological dig. Archaeologists in Cyprus have uncovered a thousand-year old fortress rampart beneath an ancient burial mound. iStock / Getty Images Plus

"Its [north-east] corner survives to a height of six meters [20 feet], and this makes it one of the most significant monuments of the 'Age of the Cypriot Kingdoms,'" said the statement.

There are a variety of techniques used by archaeologists to determine the age of the artifacts that they find buried.

According to National Geographic, relative dating involves estimating the age of an object by comparing it to the age of things around it: stratigraphy assumes that sites are layered in order of time period, with older layers beneath newer ones, while seriation, involves a groups of artifacts from the same site being statistically analyzed and put into chronological order to estimate the age of the site.

Relative dating is considered imprecise, however, so archaeologists also utilize absolute dating techniques to get a more accurate estimate of age.

Radiocarbon dating can only be used to date organic matter by measuring the amount of carbon-14 present in the sample and comparing this against an international reference. The difference determines how much the carbon isotope has decayed, and therefore how old it is.

Other absolute dating techniques include dendrochronology, which uses tree rings to estimate the age of wooden objects, thermoluminescence for dating rocks and crystals, and obsidian hydration for estimating the age of volcanic stone tools.

The rampart was preserved underneath around 484,000 cubic feet of marl and red soil. About 200 feet of the rampart has now been uncovered by the archaeologists.

According to the Department of Antiquities, the ancient city-state of Paphos from the Cypro-Classical period built the monumental rampart on Laona.

The archaeologists don't know who built the mound, however.

"The tumulus was constructed with local soils and sediments, but since there are no tumulus builders recorded from ancient Cyprus, the engineers with the required expertise must have been non-Cypriots, maybe Macedonians," Giorgos Papantoniou, an assistant professor of ancient visual and material culture at Trinity College Dublin, who was not involved in the excavation, told LiveScience.

After being uncovered, archaeological sites like this rampart monument are vulnerable to decay and damage.

Archaeologists usually protect the site using shelters, and removing delicate organic materials for preservation. As climate change gets worse, it may become more difficult for archaeologists to protect sites from the increased rates of rainfall, droughts and rising sea levels.