Piazza Arg is the first and oldest square in the capital. In the past this square, which dates back to the Zand era, was known by the following names: Shāh Square, Tupkhāneh Square-due to the presence of several cannons including the Golshan Pearl-Garden Cannon, Piazza Arg, Takhte pol-e to access them they had built a wooden bridge over the canal.
Within the Safavid walls (Shah Tahmasbi) there was a complex named "Arg-e Tehrān", (citadel of Tehran) which included: the bastion, the canal, the bridge, the naghāreh khāneh (where drums were played and horns) dating back to the Safavid period and today a small part of that large square Arg is known as the square 15 khordād.
The citadel of Tehrān at the time of Nasreddin Shāh, included a courtyard that today is a limited space between the south wing of Imam Khomeini Square and includes a section of the Imam Khomeini Street, part of the 15 khordad road to the Golubandak crossing. the Nāser Khosrow road and the Khayyām road from Golubandak to the Imām Khomeini street.
Around the Piazza Arg stood some buildings including: the great portal or "Ali Ghāpu" to the north, the notary office to the northwest; the naghāreh khāneh to the south, the telegraph building to the east and the time of Nasreddin Shāh the cannons of the square Arg, which was much larger than today, were collected, a large octagonal pool in the middle of the square and around this Two stone paved sidewalks were built for the passage of chases, etc. This square had even a small multilateral building where the "justice box" was located where people poured out their complaints or written requests. A cassette that was opened weekly and whose contents were brought and examined by Nasreddin Shāh.
At the time of Rezā Shāh large parts of the citadel of Tehrān, including the walls around it, the Bāb Ali portico, the telegraph building, the tekkie-ye doulat (building where funeral memorials took place in the days of Āshurā ) the orange garden, the Golshan garden and the internal buildings were destroyed and with the passage of time the Arg square became smaller and here were built other buildings such as the National Bank branch bazaar, the court building, the radio station etc..