Old Delhi Sites
When Shah Jahan moved his capital to Delhi in 1648, he undertook massive building projects as a tangible symbol of his imperial majesty (especially vis-a-vis Persia's Safavid Dynasty, with whom the Moghuls competed for status).
Traditional Islamic cities had three central areas: the primary mosque (patronized by the ruler), the palace (his residence), and the market. Old Delhi follows this pattern exactly
The Jama Masjid ("people's mosque") is a massive structure whose grandeur was intended to burnish Shah Jahan's prestige. It is decorated simply but expensively. As with Agra's fort, the Red Fort served as a fortress/military base, government offices, and royal residence. The royal apartments are unexpectedly small, since the royals probably spent much of their time in the adjoining gardens. The Pearl Mosque on the Fort's grounds was the emperor Aurangzeb's private mosque. Chandni Chowk (the market), is still an important commercial center, both for merchants selling things and for day laborers seeking casual employment.
It's a very different story at Gurudwara Sisganj, where the 9th Sikh guru was executed by the Mughals in 1675. Guru Tegh Bahadur came to Delhi to confront the emperor and proclaim freedom of conscience as a human right--in essence, courting martyrdom. At that time the spot he was executed was the central police station, but when Sikh armies conquered Delhi in 1783, they took control over this and other Delhi sites associated with their Gurus. All Sikh Gurudwaras have a prayer hall where the scriptures are sung, and a langar (free kitchen) where any hungry person can come for a meal.