Also known as: Semnan Central Mosque, Jameh Mosque of Semnan, Masjid-e Jameh-e Semnan

Semnan Central Mosque (Jame Mosque) was constructed in the 1st century AH on the site of the ruins of an ancient Fire Temple. Evidences can be noted here from the Mongol and Timurid periods. Its tall brick made porch on the western side of the courtyard, was constructed under the orders of a minister Khajeh Shamseddin Balijeh Semnani and the dome by Khajeh Abu Saeid, the former during the reign of Soltan Shahrokh Teimoori and the latter in the times of Sultan Sanjar.

There is an inscription on the upper portion of the porch, under which are a few huge tablets of stone. Two of which are decrees of the Safavid monarch to the public. The area for nocturnal prayers in the southern section has sixteen round pillars in the center and eight and a half columns towards the eastern wall which form the pillars of the ceiling in this vicinity. This portion was constructed during the times of Arqoon Khan, under the supervision of his minister Sheikh Alaoddoleh Semnani.

Semnan Central Mosque was repaired during the reign of Fathali Shah Qajar under the orders of Zulfaqar Semnani. To the south east of this area is the Saljuqi minaret, currently rising to the height of 31.20 meters and with a circumference of 5.5 meters On the top of this minaret is an inscription affixed on the intricate brick work, showing the date of construction.

The crown of the minaret is octagonal, with arches in brick works, in addition to the blue tiles. The area where the 'Azan' or the call for prayer is read is railed off with a beautiful wooden latticed worked railing.