Zanjan’s Soltanieh Dome which is about 54 meters high and is about 700 years old has a very unique mosaic and brick design and architecture.  This dome is the third biggest dome in the world after Santa Maria Del Fiore church’s dome in Florence, Italy, and Hagia Sophia mosque’s dome in Turkey.  Soltanieh Dome was listed as a UNESCO national heritage site by UNESCO in 2005.  However, this heritage site is now facing a number of architectural problems including deep cracks, chipping of mosaic tiles, discoloration of frescos.  In addition, it looks like water has been getting into the building through the cracks in the structure.  This historical dome like many other historical sites in Iran is suffering from wrong repair methodology and upkeep as well as absence of technical expertise in preservation of these sites. This has resulted in the dome to become heavier in weight and has changed in shape and it now looks very different from the original design.  The latest problems that this site faces are the residential buildings which have been built in the vicinity and close proximity of this national heritage site.  This situation could soon result in UNESCO’s re-listing the site as an in-danger heritage site.