The architecture of India is rooted in its history, culture and religion. Indian architecture progressed with time and assimilated the many influences that came as a result of India's global discourse with other regions of the world throughout its millennia-old past. The architectural methods practiced in India are a result of examination and implementation of its established building traditions and outside cultural interactions.
Though old, this Eastern tradition has also incorporated modern values as India became a modern nation state. The economic reforms of 1991 further bolstered the urban architecture of India as the country became more integrated with the world's economy. Traditional Vastu Shastra remains influential in India's architecture during the contemporary era.
The Indus Valley Civilization (IVC) was a Bronze Age civilization (3300–1700 BC; mature period 2600–1900 BC) in the northwestern region of the Indian subcontinent, consisting of what is now mainly modern-day Pakistan and northwest India. Flourishing around the Indus River basin, the civilization primarily centred along the Indus and the Punjab region, extending into the Ghaggar-Hakra River valley and the Ganges-Yamuna Doab. Geographically, the civilization was spread over an area of some 1,260,000 square km, making it the largest ancient civilization in the world.
The Indus Valley is one of the world's earliest urban civilizations, along with its contemporaries, Mesopotamia and Ancient Egypt. At its peak, the Indus Civilization may have had a population of well over five million. Inhabitants of the ancient Indus river valley developed new techniques in metallurgy and handicraft (carneol products, seal carving) and produced copper, bronze, lead, and tin. The civilization is noted for its cities built of brick, roadside drainage system, and multistoried houses. The baths and toilets system the cities had is acknowledged as one of the most advanced in the ancient world. The grid layout planning of the cities with roads at exact right angles is a modern system that was implemented in the cities of this particular civilization. The urban agglomeration and production scale of this particular civilization was unsurpassed at the time and for many future centuries.
The mature phase of this civilization is called the Harappan Civilization, as the first of its cities to be unearthed was located at Harappa, excavated in the 1920s in what was at the time the Punjab province of British India (now in Pakistan). Excavation of Harappan sites has been ongoing since 1920, with important breakthroughs occurring as recently as 1999. To date, over 1,052 cities and settlements have been found, mainly in the general region of the Ghaggar-Hakra river and its tributaries. Among the settlements were the major urban centres of Harappa, Lothal, Mohenjo-daro (UNESCO World Heritage Site), Dholavira, Kalibanga, and Rakhigarhi.