The bulbous, marble domes of the Jama Masjid ('Friday Mosque') cover the main prayer hall of the largest mosque in India. Twenty-five thousand worshippers can fit in to its vast courtyard and together with the Red Fort, it dominates the cramped markets and winding alleyways of Old Delhi. Started in 1644, it proved to be the last building commissioned by the most architecturally prolific of the moghul emporers, Shah Jahan.