Jantar Mantar

Jantar Mantar is an 18th-century astronomical complex with 19 enormous stone and marble instruments that still function today.

Here you can see the world's largest stone sundial, the Samrat Yantra (27 meters high), along with instruments for measuring time, tracking the stars and other celestial bodies and making calendar calculations.

Essentially, it's an open-air astronomy museum: you can examine everything up close, and many devices have explanations in English.

A visit takes 40–60 minutes; it's best to come in the morning or late afternoon – there is little shade during the day.

It's convenient to combine with City Palace: they stand next to each other, with entrances across the street from one another.

A historic open-air observatory