Isfahan is Iran’s third most populous city (after Tehran and Mashhad) and the center of Isfahan province. It is the second most visited tourist city after Mashhad and Iran’s second industrial city after Tehran. This city was the capital of Iran in the heyday of post-Islamic Iran during the Safavid era in which, many historical monuments have survived from that time. Isfahan is a city of four seasons. Its summers are warm and winters are cold. The best time to travel to Isfahan is mid-spring. The city is renowned for its beautiful Islamic architecture, covered bridges, mosques, and unique minarets. In December 2015, along with Rasht, the city joined UNESCO as the first Iranian city to join the network of creative cities of the world. According to UNESCO standards, the creative city is a city that harnesses the innovation and empowerment of citizens in sustainable urban development. This city has fifteen metropolitan areas. Naqsh-e Jahan Square is a prominent example of Islamic architecture. Other monuments in Isfahan include Menarjonban, Thirty-Three Bridges, Khaju Bridge, Chehel-column Palace, Ali-Qapo Mansion and many other historical sites.