TEHRAN -- Tiles on the dome of the Imam Mosque slowly creeping downward with time have exposed distinct curves on the underlying surface.

The mosque is a part of Isfahan’s Naqsh-e Jahan Square, a complex of Safavid-era monuments registered on UNESCO’s World Heritage List.
The curves can be easily seen on southern surface of the dome and are visible even at a great distance, the Persian service of ISNA reported on Friday.
The dome had been resorted in a 12-year project that was completed in 2007.
“Unfortunately, signs of damage have appeared on the surface of the dome on the south side of the structure, which is subjected to long-term exposure from atmospheric conditions like wind, rainfall, and the sun,” restoration expert Hamid Mazaheri told ISNA.
“The tiles are warmed and cooled by the sun and rainfall. Over time, this heating and cooling has caused the tiles to separate from the main body of the dome, causing them to creep downward,” he added.
He urged the Isfahan Cultural Heritage, Tourism and Handicrafts Department to take an action to stop destruction of the dome.
He said that dome is the most beautiful but most vulnerable part of mosques and other Islamic monuments employing this type of structure.
Experts believe that the curves began to appear after a large number of tiles installed on the dome during the Safavid era were replaced with new ones in the latest restoration project.
A restoration project carried out last year in a part of the Naqsh-e Jahan Square’s second floor known as Hojreh resulted in addition of another destructive factor to the site.
The use of heavy mortar in restoring the site caused wide cracks in the ceiling and experts said that catastrophic irreversible damage could be expected.
The Naqsh-e Jahan Square, which also comprises the Sheikh Lotfollah Mosque, the Aali-Qapu Palace and the Qeisarieh Bazaar was registered on UNESCO World Heritage List in 1979.
Photo: Crude restoration has caused distinct curves on the dome of the Imam Mosque at the Naqsh-e Jahan Square Isfahan. (ISNA/Mehrdad Moslemzadeh)