While walking through Wigan town centre, coming across the underground heating system for a Roman bath house may not be one of the things you expect to see. Beside the Grand Arcade Shopping Centre, on the Millgate street side is a reconstruction of the hypocaust (underfloor heating system) using some of the actual building materials found in a fairly recent archaeological dig.
Before the new shopping centre was built, archaeological digs were carried out in the area as it has long been known that Wigan was the site of Roman activity. In the area that was known as Mc Ewen’s yard (now covered by the shops) the foundation of a large building was discovered. It had nine rooms, each differing in size, and in three of the rooms were the tell tale discovery of the heating system. These were stacks of square tiles (or pilae) which were spaced at regular intervals. The pilae would have held up the floor above, and also provided a space underneath for hot smoke and air to circulate. Furnaces were located outside and sent hot air and smoke through the hypocaust which would then exit through the flue pipes in hollow wall tiles set into the walls. This allowed some of the rooms to have heated floors and walls. The reconstruction clearly shows the pilae stacks, floor tiles and hollow wall tiles and has useful interpretation boards to give some background to the site.
Hot water for the baths was heated in lead boilers placed above the furnaces. It could be that the water for this was taken from the nearby River Douglas, or it may have come from local springs. Some Victorian accounts say that the springs in Wigan were sulphurous like those in Harrogate (The stench of sulphur can still be smelt at some of the well heads of Harrogate, and only the foolhardy would try drinking the water which is still offered to unsuspecting visitors).
The building was grand, having a colonnade of large pillars at its entrance. Window glass was also discovered in the excavation, again adding to its status. Other glass findings include a small bottle probably for bath oil, a glass beaker and funnel. All of the important artefacts were given to the Museum of Wigan Life, located nearby on Library Street.
Bathhouses were made of stone, because of the considerable risk of fire. They were also built away from other buildings for the same reason. This particular building was larger than the ones found at two of the forts on Hadrian’s Wall (Great Chester and Carrawburgh), which both had around 500 troops. This gives us a hint to how big the garrison was at Wigan.
The Roman fort at Wigan, known as Coccium, was built early on in the Roman campaign into North West England, probably around 70 AD. It was only ever an earth and timber fort, never made into stone unlike the ones at Manchester, Ribchester and Lancaster. These three all became stone and remained garrisoned for some time. By 160 AD the Romans decided to move the army away from Wigan and accordingly the bath house and fort were demolished. In the bath house much of the wall stone, floor tiles and hollow wall tiles were taken away (the wall stone was probably to be reused) as the excavators only found the print of the foundation trenches. The roof tiles were left in the ruins, over a tonne of them were found in the archaeological dig. Part of one of the colonnade columns was also dropped into the hypocaust.
Dismantling of Roman military buildings was a common occurrence by the army. If they 
left a fort and its associated site, they never wanted anyone hostile to have use of something that could be so easily defended. Roman activity continued into the next century at Wigan, evidenced from the pot fragments found on the in the area, but what was going on is open to speculation at this point.
If you walk up the hill towards the library you can see more historical interpretation boards and stand within the space where the fort used to be. You can then head over to the museum nearby to see some of the artifacts.
Site visited by A. and S. Bowden 2014
Opening Times: The site is free to visit at any reasonable time, being located in an open ‘square’ area behind the Grand Shopping Arcade on the Millgate side (look for the large Debenhams sign on the outside of the shopping centre). There are some interesting maps on the walls in the square, showing Wigan through the ages.
Parking: Park at the Grand Arcade Shopping Centre. There is a charge to park.
Nearby, just a few moments away on foot
Mab’s Cross, Standishgate, Wigan
A drive away
The Lost Church of St Stephen’s
Sources:
Discovering Coccium: The Archaeology of Roman Wigan: Greater Manchester’s Past Revealed (3): Ian Miller and Bill Aldridge (2011), Oxford Archaeology Ltd
Website
The Museum of Wigan Life http://www.wlct.org/wigan/museums-archives/mowl/
Lancashire Past 
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