Recent rainfalls in southern Iran have gravely endangered the Achaemenid site of Persepolis near the city of Shiraz in Fars Province in Iran.
Water has gathered at the foot of Persepolis columns and disrupted visits to the ancient site, CHN reported.
Experts say water will cause serious erosion in the age-old structures.
Persepolis is the oldest city with a sewage system and most of its canals are still functional.
Reports, however, say that some canals are clogged and heavy rainfalls have caused huge amounts of water to gather at the site and workers cannot stop its flow.
"Upon entering the site, I realized that I should have checked the weather forecast to enjoy my visit here," said a tourist as he walked in water coming up to his ankle.
"I got the chance to visit Persepolis after so many years, but unfortunately it is not possible to see all parts of the complex," he added.
Head of the Iranian Association of Hafez Studies, who was also visiting Persepolis, said the site was built based on its geographical location.
"Since Persepolis was built at the foot of Rahmat , it was threatened by floods," said Mehran Mohammadi.
"The sewage system and canals were built to carry water in case the city was flooded, but most of them were destroyed during later wars," he added.
Mohammadi said that officials should have plans to protect Persepolis against natural disasters such as floods and earthquakes.
Another visitor from the southern Iranian city of Yazd said if the current situation is not resolved the whole site will be submerged.
"Many parts of Persepolis have remained safe because of the functioning canals, but the amount of water is now so much that many of the ancient passages have been clogged," he added.
The main capital of the Achaemenid Empire, Persepolis was built in 518 BCE on an immense half-artificial, half-natural terrace by Darius I, who created an impressive palace complex inspired by Mesopotamian models.
The site was registered on the UNESCO World Heritage List in 1979.