Sultaniye is a historical town located in the Zanjan province of Iran. It is known for its rich cultural heritage and significant architectural sites, including the famous Sultaniyeh Dome, which is a UNESCO World Heritage Site. This dome is one of the largest brick domes in the world and showcases the unique Persian architectural style. The town was established in the 14th century during the Ilkhanate period and served as a capital for a time. Sultaniyeh is also notable for its ancient caravanserais and mosques, reflecting the region's importance as a trade and cultural center in the past.