Although Moynihan was describing another monument with this text, it applies precisely to Humayun's Garden Tomb and its enclosure wall.
Enclosures for tombs were not unknown in India [...] The concept of setting monumental tombs within a large enclosed char bagh, however, was the Mughal's major contribution to garden architecture. The designs of tomb and garden were treated as one; the setting enhanced by the beauty of the monument. Symbolically, it was far more—as the perfect embodiment of the ancient ideal, it was the ultimate Paradise Garden. The large square enclosure, divided with geometric precision, was the ordered universe; in the center, the tomb itself rose like the cosmic mountain above the four rivers which were represented by water channels1.
Humayun's Garden Tomb's enclosure wall not only defines the space as a garden tomb but ties the garden's secondary buildings in as part of the garden. The hammam, the baradari, the wall mosque, the wall shared with the Nila Gumbad's site, and, most importantly, Nizam al-Din's Chilla Khana are actually part of the wall. One could say that the wall is built of rubble masonry and buildings.
1. Elizabeth B. Moynihan, Paradise as a Garden In Persia and Mughal India (New York: George Braziller, 1979), 111.
Kruche, Krupali Uplekar, Danny Aijian, Selena Anders, Iva Dokonal, and Jill Kapadia. "History, Morphology and Perfect Proportions of Mughal Tombs: The Secret to Creation of Taj Mahal." International Journal of Architectural Research 4, no. 1 (2010): 158-78.
Wescoat Jr., James L. "The Islamic Garden: Issues for Landscape Research." In Environmental Design: Journal of the Islamic Environmental Design Research Centre 1, edited by Attilo Petruccioli, 10-9. Rome: Carucci Editions, 1986.