The Brihadeeswarar Temple in Thanjavur, Tamil Nadu, is one of the largest stone structures in the world, constructed in the 11th century.

Rani ki Vav is a stepwell located in Patan, Gujarat, known for its intricate carvings and architectural beauty.

The Karez system, an ancient underground water management system, is still in use in many parts of India, providing water for irrigation and drinking.

The Ujjain Observatory, located in Ujjain, Madhya Pradesh, is one of the oldest observatories in the world, dating back to the 5th century BCE.

Lothal, an ancient port city located in Gujarat, was a major center of trade and commerce during the Indus Valley Civilization.

The Kallanai Dam, located in Tamil Nadu, is one of the oldest dams in the world, built across the Kaveri River in the 2nd century CE.

Mohenjo-daro, an ancient city located in Pakistan, was known for its advanced water management system, including underground channels and reservoirs.

The Iron Pillar of Delhi is an ancient iron pillar located in Delhi, famous for its resistance to corrosion and its intricate carvings.

The Kailasa Temple, located in Ellora, Maharashtra, is known for its intricate stone carvings and is considered one of the largest monolithic structures in the world.

The Gnomon, a simple astronomical instrument, was used in ancient India to measure time and track celestial bodies.

Dwarka, an ancient city located in Gujarat, was known for its advanced shipbuilding techniques and maritime trade.

The Sulba Sutras, a collection of ancient Indian mathematical texts, contains the earliest known use of the decimal system and the concept of zero.

Brahmagupta, an ancient Indian mathematician, is credited with developing the concept of negative numbers and the use of decimal fractions.

Bhaskara II, an ancient Indian mathematician, developed the Fibonacci sequence and the Pascal's triangle.

Madhava of Sangamagrama, an ancient Indian mathematician, is known for his contributions to trigonometry, including the development of the sine and cosine functions.