One of the most fascinating aspects of Delhi is the "visibility" of its historic past. Were it not for the demands of urbanization, large portions of the city could well be earmarked as archaeological parks. This is because the rulers of successive dynasties between the 13th and the 17th centuries established seven cities in different parts of Delhi. A chronological review of these cities fortunately also serves as a suitable itinerary for tourists and highlights the important monuments amongst the 1300 officially listed.

Delhi's history goes much further back in time than the 13th century. In 1955, excavations at the Purana Qila revealed that the site was inhabited 3000 years ago. Ware pottery known as Painted Gray Ware and dated to 1000 BC confirmed this as being yet another site associated with the epic Mahabharata. The excavations also cut through houses and streets of the Sultanate, Rajput, post-Gupta, Gupta, Saka-Kushan and Sunga periods, reaching down to the Mauryan era (300 BC), thus revealing almost continuous habitaion. The association of Emperor Ashoka (273-36 BC) with Delhi has come to light with the discovery of a Minor Rock Edict in the locality known as Srinivaspuri.

A clearer picture of the city emerges from the end of the 10th century, when the Tomar Rajputs established themselves in the in the Aravalli hills south of Delhi. The isolated, rocky outcrop facilitated the defence of the royal resort which the Rajputs called Dhilli or Dhillika. The core of the first of the seven cities was created by Anangpal Tomar who is said to have built Lal Kot, which is the first known regular defence work in Delhi. The Chauhan Rajputs later captured Delhi from the Tomars . Prithviraj III, also known as Rai Pithora, extended Lal Kot, adding massive ramparts and gates, and made Qila Rai Pithora the first city of Delhi.

Today, only the ramparts are visible near the Qutub Minar , though the city is known to have had several Hindu and Jain temples. Prithviraj was ruling Delhi when Muhammad of Ghur invaded India, and died fighting the invader at the Second Battle of Tarain in 1192. Ghur returned, but left as his viceroy, his slave Qutbuddin Aibak.

In 1206, Qutbuddin crowned himself as the Sultan of the Slave or Mamluk dynasty, and became the first Muslim ruler of Delhi. Qutbuddin, had however, commenced his architectural career even before he chose to become the sultan. The mosque was essential to the Islamic emphasis on congregational prayer, while the burial of the dead, as opposed to cremation, introduced the tomb to India.

The earliest of these Islamic structures are to be seen in the Qutub complex and the incorporation of many Hindu elements is due to the ready availability of building material and the use of local craftsmen. Qutbuddin raised the Quwwat-ul-Islam (might of Islam) mosque, which is the earliest extant mosque in India. Within its spacious courtyard he retained the 4th century Iron Pillar, probably the standard of an ancient Vishnu temple. The pillar has puzzled scientists, as its iron has not rusted in all these centuries.

In 1199, Qutbuddin raised the Qutub Minar either as a victory tower or as a minaret to the adjacent mosque. From a base of 14.32 mtrs it tapers to 2.75 mtrs at a height of 72.5 mtrs. It is still the highest stone tower in India, one of the finest tower Islamic structures ever raised and Delhi's recognized landmark. It was completed by the Sultan's successor and son-in-low, Iltutmish. The tomb of Iltutmish, which he himself built in 1235, is nearby. Its interiors are profusely decorated with calligraphy, thought the dome has collapsed.

The Khalji rulers displaced the Slave dynasty in 1290, and when Alauddin Khali ordered renovations of the mosque in 1311, he also raised the impressive Alai Darwaza, the southern entrance to the mosque. It is the first example of a building employing wholly Islamic principles of construction, including the true arch. In 1303, Alauddin, established the second city of Delhi, called Siri, of which nothing remains but the embattlements. He also had dug a vast reservoir, Hauz Khas, to sypply water to his city.

Contemporary historians describe the Delhi of that time as being the "envy of Baghdad, the rival of Cairo and the equal of Constantinople". (for the sake of convenience, tourists visiting the Qutb complex could also see the Tomb of AdhamKhan and Zafar Mahal in Mehrauli, and the Tomb of Jamai-Kamali behind the Qutb Minar. These, however, belong to a later date.) The Khalhjis were replaced by the Tughlaq dynasty in 1321. of its eleven rulers, only the first three were interested in architecture and each of them established a new city.