Imam Mosque, is a mosque in Isfahan, Iran standing in south side of Naghsh-i Jahan Square.Built during the Safavid period, it is an excellent example of Islamic architecture of Iran, and regarded as one of the masterpieces of Persian Architecture. The Shah Mosque of Esfahan is one of the everlasting masterpieces of architecture in Iran. It is registered, along with the Naghsh-i Jahan Square, as a UNESCO World Heritage Site. Its construction began in 1611, and its splendor is mainly due to the beauty of its seven-colour mosaic tiles and calligraphic inscriptions. The mosque is one of the treasures featured on Around the World in 80 Treasures presented by the architecture historian Dan Cruickshank. The mosque is depicted on the reverse of the Iranian 20,000 rials banknote. The port of the mosque measures 27 m (89 ft) high, crowned with two minarets 42 m (138 ft) tall. The Mosque is surrounded with four iwans and arcades. All the walls are ornamented with seven-color mosaic tile. The most magnificent iwan of the mosque is the one facing the Qibla measuring 33 m (108 ft) high. Behind this iwan is a space which is roofed with the largest dome in the city at 52 m (171 ft) height. The dome is double layered. The whole of the construction measures 100 by 130 metres (330 x 430 ft), with the central courtyard measuring 70 by 70 metres (230 x 230 ft).