[7][8] The city was developed under the rule of the Safavid and Qajar Empire and is home to historical buildings and memorials from those eras.

This city has a unique climate due to access to natural resources such as many trees, rivers, and green plains.

[13] The large Shah-Abbasi Caravansarai, located at the southeast of Towhid Square, was built in the same era, under the rule of Šāh Esmāil.

In 1810, the Qajar prince Soleyman Mirza built the Soleymaniyeh Palace at Karaj to serve as a summer resort.

[13] The palace had four towers and was surrounded by gardens, and its reception room featured a pair of paintings by Abdallah Khan Naqqashbandi.

[13] This "Industrial Model Town of Karaj" was intended to be the site of the country's first steel mills, capitalizing on easy access to water and coal from the Alborz.

[13] However, the construction equipment imported from Germany was impounded by the British going through the Suez Canal in 1940, and the planned complex was never built.

[13] This complex, called Shahrak-e Jahanshahr, included oil, tea, and textile factories as well as housing for the workers.

The villages Hesārak, Gowhar Dašt, and Šahrak e Azimie are located in the northern Greater Karaj.

The city is a starting point for a drive along road forced north through the Alborz mountain to the Caspian Sea.

The establishment of the factory Zowb Āhan e Karaj was halted by the beginning of the Second World War, and it was never launched.

The special economic zone of Payam, with an area about 3,600 ha (36 km2; 8,900 acres) within the territory of Payam International Airport, was established in Karaj for development of air cargo and postal transportation, cold store, and packing services, as well as perishable and time sensitive exports.

Karaj was one of the few Iranian cities in the 2010s that controlled the damage to the environment in the process of producing women's clothing.

Karaj women's over-the-knee boots are exported to the whole country and have a significant contribution to the city's economy.

The aerial transport of Karaj is served by the Payam International Airport, which was established in 1990, and was officially opened in 1997.

The second line of Karaj metro (north to south) is under construction and opened for limited service in February 2023.

Currently, this airport and its special area are used for purposes such as cargo transit, commercial transportation, and goods mail in the development of the country's communication and information technology industries.

[citation needed] Educational and research centers of the city include: Abū Bakr Muḥammad ibn al Ḥasan al-Karajī (Persian: ابو بکر محمد بن الحسن الکرجی; c. 953 – c. 1029) was a 10th-century Persian mathematician and engineer who flourished at Baghdad.