One would be tempted to think and argue that the cities of Delhi were in reality less or more than seven. But the accepted number is seven (excluding New Delhi) and these are cities whose remains are extant. Historians speak of the “Seven Cities of Delhi” but, between 1100 A.D. and 1947 A.D., there have been eight of them:

• The oldest city near the site of the Qutab Minar-Mahrauli
  

Mehrauli  is in the neighbourhood in the South West district of Delhi in India. It . The area is located close to Gurgaon and next to Vasant Kunj.

• Siri
  

Siri was built during the rule of Ala-ud-Din Khalji of the Delhi Sultanate to defend the city from the onslaught of the Mongols. It was the second of the seven cities of medieval Delhi built around 1303 (stated to be the first entirely constructed by Muslims), which at present is seen only in ruins with a few remnants.

• Tughlqabad
  

Built by Ghiyas-ud-din Tughlaq, the founder of Tughlaq dynasty, of the Delhi Sultanate in 1321, which was later abandoned in 1327. It gets its name from the nearby Tughlaqabad area. Tughalaq also built Qutub-Badarpur Road, which connected the new city to the G.T Road. The road is known as Mehrauli-Badarpur Road.

• Jahanpanah
  

Jahanpanah was the next (fourth) city of Delhi established in 1326–1327 by king Muhammad bin Tughlaq (1321–51), of the Delhi Sultanate. To ward off the perpetual threat of the Mongol warriors, Tughlaq built the fortified city of Jahanpanah ( which means in Persian: “Refuge of the World”) absorming the Adilabad fort that had been built in the 14th century and also all the establishments lying between Qila Rai Pithora and Siri Qila.The city doesn’t exist now.

• Firozobad
  

Firozobad was built by Sultan Feroz Shah Tughlaq to house his concept of  Delhi city called Ferozabad. A gleaming polished pillar from the 3rd century B.C. rises from the palace’s crumbling remains, one of many pillars of Ashoka left by the Mauryanemperor; it was moved from Pong Ghati Ambala, Punjab (currently in Haryana) and re-erected in its current location in 1356.

• The city around Purana Qila
  

Purana Qila is oldest among all forts in Delhi and, in fact, the oldest known structure of in Delhi. It was rebuilt by the  Sher Shah Suri, on the same site, which was perhaps also the site of Indraprastha, famously believed to be the capital of the legendary Pandavas. Sher Shah built Purana-Qal’a with an extensive city-area sprawling around it. Purana Qila was still incomplete at Sher Shah’s death in 1545, and was completed by his son Islam Shah or Humayun, although it is not certain which parts were built by whom. It’s located at the site of the legendary city of Indraprastha; that was founded by Pandavas on the banks of perennial river Yamuna, which is revered by Hindus since ages, points to the possibility of this site’s history dating back to nearly more than 5000 years old. Consequently, the fort is considered by some, to be ‘the first city of Delhi. Researchers now confirm
that up to 1913, a village called Indrapat existed within the fort. Excavations by Archaeological Survey of India  at Purana Quila in 1954-55 ( and again 1969 to 1973 have unearthed Painted Grey Ware dating 1000 B.C

Shahjahanabad (Old-Delhi)

Old Delhi or Purani Dilli as it is known today , was built and named as Shahjahanabad  by Mughal Emperor  Shahjahan in A.D 1639. Old Delhi functioned as the capital city of the Mughals until the end days of the Mughals  It once housed mansions of nobles and members of the royal court and elegant mosques and gardens. Today, despite having become extremely crowded, still serves as the symbolic heart of metropolitan Delhi.

• New Delhi
  

New Delhi or Lutyens’ Delhi is an area in Delhi, specifically New Delhi, India.It was named after the leading British architect Edwin Lutyens (1869–1944), who was the architect and designer of New Delhi including the Lutyens Bungalow Zone (LBZ).Today’s Delhi is a modern city and is well knit on the internet world.

The foundation stone of the city was laid down by George V,  during famous Delhi Durbar held in 1911. It was designed by British architects, Sir Edwin Lutyens and Sir Herbert Baker. The new capital of India was inaugurated on 13 February 1931, by Viceroy Lord Irwin.

    Each of these cities grew round a particular palace – fort of a particular dynasty and every dynasty wished to have a new seat pf power for consideration of prestige. Even the Kings of the same dynasty had this ambition and realized their dream if they had the resources to do so. With each successive reign, some distinctive architectural features were added. Often some important new buildings would, rise, something monumental – whether a mosque or a tomb, a palace, a fortress or a victory-tower.

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Green Belt in Indian Cities