A city in two parts
Mohenjo-Daro sits on the Indus plain in Sindh, Pakistan, and was occupied during the mature phase of the Indus civilization, broadly 2600-1900 BCE. The name, usually translated “mound of the dead”, is a modern one; the ancient name is unknown. Like many Indus cities it has two main parts: a smaller, raised western mound, normally called the citadel, and a much larger eastern area, the Lower Town, whose street grid and houses are a separate subject.
The citadel stands on a platform of mud brick and rubble, several metres high, faced with fired brick. Early excavators saw it as a defensive fortress, hence the term, but most scholars now think the walls and platform also served to protect against flooding and to mark off a special zone. Whether it was a seat of rulers, a religious precinct, or both, is not known.
What stood on the citadel
Several large structures have been identified on the mound, though their labels were given by excavators and are not firmly established:
- the Great Bath, a large rectangular brick tank in a courtyard;
- a large building to the west of it that Mortimer Wheeler named the “Granary”, on the idea that it stored grain. Later scholars have questioned this, partly because there is little evidence of grain in it;
- a pillared hall to the south, which could have been an assembly space or market, although this is a guess;
- a group of residential or administrative buildings, and later a Buddhist stupa and monastery built on top of the mound in the early centuries CE, long after the Indus city was gone.
The stupa is worth remembering: it means the mound has a long later history, and parts of the top were disturbed by later building.
The Great Bath
The Great Bath is the best-known structure at the site. The brick pool is commonly described as about 12 metres long and 7 metres wide, and roughly 2.4 metres deep, though published measurements differ slightly. Steps lead down into it at both ends, and the floor slopes toward a drain. It sits in a paved court surrounded by rooms and a colonnade or verandah, with a well nearby.
How it was made watertight
The construction is the most secure part of the story. The pool was lined with carefully fitted fired bricks, set on edge with gypsum mortar, and a layer of bitumen, a natural tar, was applied between brick layers or behind the lining to seal it. Outside the main lining there was a further wall of brick. A corbelled outlet, built into one corner, carried water into a large drain. Together, these show builders who understood how to waterproof a large basin and drain it again. Water engineering of this kind is usually associated with much later cultures, as in Roman aqueducts, though the Indus builders worked on a smaller scale and with different materials.
Was it a ritual pool?
Many popular accounts call the Great Bath a ritual or sacred pool, and some link it with later Indian traditions of bathing for purification. This is possible, but it is a hypothesis rather than a finding. Nothing found in the pool or its surroundings, such as an inscription, an altar or a statue of a deity, tells us what it was used for.
Reasons for caution:
- Indus houses had private bathing areas, so a large communal bath did not have to be used for hygiene alone.
- No temple has been clearly identified anywhere in the Indus world, so there is no firm context for religion at the site.
- Ideas drawn from later South Asian religion cannot automatically be projected back over a thousand years or more, especially when we cannot read the Indus script.
- Alternative suggestions include a public bathing facility, a place for ceremonies of status, or a reservoir for some other purpose.
In short, “ritual bath” is a reasonable possibility, but “public bath” and “ceremonial tank” are both interpretations, and archaeologists generally describe the function as unknown.
What the citadel suggests
Even without answers to the function question, the citadel shows organised labour. Lifting a platform of this scale, producing great numbers of uniform bricks, and designing a pool with a drain required planning and a workforce under some kind of direction. The same impression comes from other Harappan civilization sites, where citadels and large platforms are common. The absence of royal tombs or palaces makes it harder to say who gave the orders.
Conservation and what is visible today
Mohenjo-Daro was inscribed as a UNESCO World Heritage Site in 1980. Visitors see the citadel, the Great Bath and sections of the Lower Town, though modern conservation has meant that some trenches were backfilled and some walls were capped or repaired. Salt in the groundwater and flooding are continuing concerns, as the Mohenjo-Daro excavation history and later monitoring have shown.
Because the Great Bath is a restored and partly reconstructed monument, some details visible today may reflect modern repairs rather than original fabric. If you are comparing sources, check whether a description comes from an excavation report or a later reconstruction.
Reading the evidence carefully
The Great Bath is a good example of how archaeology moves from observation to interpretation. The measurements, bricks, bitumen and drain are observations. “Ritual pool” is an interpretation. Keeping the two apart is the simplest way to avoid repeating a confident story that the evidence does not yet support.