This is of the tallest buildings in Roman Britain and the roof is 20 metres above the bath. Roman visitors are amazed by its high ceiling. However, it has been predicted by Roman fortune-tellers that in the future, the roof will be gone and the main bath will be open to the heavens.
The bubbling water of the sacred spring
The hot water in the Spring rises at a rate of 1,170,000 litres each day at 46 degrees celsius. It bubbles up and flows into the King's Bath which is predicted to be built in the 12th century AD.
Beneath the King's Bath will be a reservoir built by Roman engineers who will use the hot water to supply the baths.
Us Romans also use two smaller hot springs nearby.
Below is a video of steam escaping the Sacred Spring.
Natural steam escaping the Sacred Spring
People visit the Roman Baths, Sacred Spring and Temple of Sulis Minerva from around the Roman world. They come to bathe in sacred waters, seek healing and pray.
In the early 4th century AD the Baths and Temple of Sulis Minerva were at their greatest extent. In the courtyards and bathing halls there was space for hundreds of visitors. The buildings were colourful and buzzed with activity.
The bath house manager and his staff, temple priests, doctors, scribes, builders, servants and slaves are all needed to maintain this special place.
The earliest known inscription
This is the earliest known inscription from the baths. It is from a small monument and dates back to 76 AD, so the baths must have been built then. The inscription reads '...in the 7th consulship of the Emperor Vespasian.' This was seven years after he became Emperor in 69 AD.
The earliest coins found here were made before us Romans arrived in Britain in 43 AD. They were made by two local tribes, the Dobunni and the Durotriges.
The coins are thrown as offerings into the Sacred Spring. They show stylised images of a ship, human heads and triple tailed horses.
Forgeries are made of Imperial coins which are then used alongside the official currency.
In 248 AD Philip I and his wife Otacilia marked the anniversary of the founding of Rome with celebratory games and special coins.
The amount of silver in Roman coins was reduced over time. Mixed with copper the coins are distinctive now, but had the same value as earlier silver coins were issued.
There are only two types of coin in Rome:
Silver denii - smaller, with the male wearing a laurel wreath.
Silver radius - larger, with the male wearing a crown.
Some Roman coins
Aquae Sulis is a relatively small town in the Roman Empire. One or two thousand people live here.
Half of the people named in inscriptions come from other places in the Empire. They probably travelled to Aquae Sulis to seek healing, but many of them could have been traders looking to sell products.
To the left is a map of the Roman Empire, which shows how far some people would be willing to travel to get to Aquae Sulis.
Traders and pilgrims visiting Aquae Sulis sometimes travel long distances. They bring news and ideas as well as money and goods.
They probably stay in lodgings or guest houses. When making their way to the Temple or Baths they might be offered hot food and drink at stalls or bars.
The everyday objects that they and local people use include goods and utensils from across the Empire.
"Minerva is the patron goddess... In her temple, the eternal flames never whiten into ash."
-Solinus, 3 AD
These large stones are re-used as paving in the Temple Courtyard. They are the tops of decorated niches which must have come from a large monument.
We do not know what that is but their presence serves as a reminder that we do not know everything that happened here and that people's ideas may have changed over time.
The outer wall of the Temple Courtyard is to the left.
The massive stone blocks form a buttress supporting a corner of the building over the Sacred Spring. You can see more of this building as you walk through the Temple Courtyard.
Many skilled craftsmen were needed to build the baths. They used tools and techniques found throughout the Roman world. They were instructed by architects and supported by slaves.
"We... erect altars at places where great streams burst suddenly from hidden sources; we honour springs of hot water as divine"
-Seneca Epistulae Morales 41.3, 1st century AD
Here surplus water from the Spring pours into a Roman drain and flows on to the river.
The gif on the right is of the water pouring out from the overflow. Notice how the water is hot enough for there to be steam coming off of it.
In the 1st century AD, the Romans built a stone-walled reservoir around the Sacred Spring to supply hot water to the baths.
The overflow was built into the east wall of the reservoir. From here, water pours into the main drain and flows beneath your feet to the river Avon.
Mixed bathing is often practised in the Roman world, but not always. Here in Aquae Sulis, similar rooms to the east and west of the Great Bath allow men and women to bathe simultaneously but separately.
You will find women in the east and men in the west.
The sweet smells of massage oils, sweat and steam greets bathers as they enter these large heated rooms.
Noble and poor, slaves and free all use the baths together. Attendants help with food and drink and slaves accompany the rich, fetching and carrying and protecting their belongings.
People scrape their oiled skin clean with a curved metal strigil, have their armpits plucked by an alipilus and eat snacks such as oyster, sausages and bread.
In all this activity there is order. People move from a changing room - apodyterium, to a warm room - tepidarium, and finally to the hottest room - caldarium. There are shallow bathing pools - sudatoria, two deep immersion pools - balnea, and a large cool swimming bath - natatio.
1 - Apodyterium - Changing room
2 - Tepidarium - Warm bath
3 - Caldarium - Hot bath
4 - Natatio - Swimming pool
5 - Sudatonia - Shallow bathing pool
6 - Balnea - Immersion pool
The main bath
Water flowing from the spring to the main bath
The hypocaust was the Roman way of heating places without visible fire. In this case, to heat the baths.
The hypocaust system had a furnace that would heat the air. The floor was raised above the ground by pillars that were called pilae, which you can see in the picture to the left, so that hot air could circulate under it.
The floor consisted of a layer of tiles, followed by a layer of concrete, then another layer of tiles.
The Romans also made sure that the hot air and smokes did not leak from the floor and walls.