* Astronomy

As the country celebrates the 150th anniversary of the First War of Independence, there exists a monument on the Capital's Northern Ridge that is special not only because it was associated with the historic revolt but also because of its astronomical significance.
Built by Firoz Shah Tughlaq, the monument came to be known as Pir Ghaib after a Sufi saint "disappeared mysteriously" from the monument.
According to Nehru Planetarium Director N. Rathnasree, the monument was the centre of action during the siege of Delhi in 1857.

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