Dundonald Castle Mysteries Part 3: The Well

Written by Gwen Sinclair

Geologists have come from far and wide over centuries to study Scotland’s ancient volcanic systems and range of rock sequences across its diversity of landscapes which counts as some of the oldest, and most unusual rock formations in the world. Dundonald is no exception, and is well worth visiting to see in person the variety of geologically diverse land forms created from the after effects of the ice age where Castle Hill has served as an ideal natural vantage point providing inimitable views reaching as far as Argyllshire, Dumbartonshire and Lanarkshire. In this, the third in our series where we’re looking into some of the many mysteries surrounding Dundonald Castle, Dundonald’s unique geological story, collides with its fascinating history, as we look into the mystery of the well –  to be found cut from what was once the location of a volcano which was active around 500 million years ago! 

The well has not only been the source of water to the residents of Dundonald Castle, but has also been a source of many questions over the years!  We’re often asked how was it dug out?given that Castle Hill has a fairly thin layer of top soil covering volcanic rock and that the hill stands some 60 m above sea level!  Also we are regularly asked: why was it built outside the main walls of the castle? 

Our well can be found on the left hand side of the pathway before it reaches the barmkin wall which once surrounded the outer parameter of Robert II’s Castle built c 1371.  Barmkin is a Scots word for a defensive enclosure wall usually found in tower houses or pele towers and smaller castles in Scotland and Northern England. So this immediately begs the fair question – that where the castle household, their food supplies, and even livestock would have been kept behind this defensive wall,  why then was the water supply, not located inside Robert’s defensive enclosure?

View showing the barmkin wall in relation to the well 

To answer this we need to travel back in time a further 130 or so years since what we do know is that the well seems to have originated inside what may have been the South tower of the East facing Gatehouse of Alexander’s Dundonald Castle built c1241 – which constituted a time of major building on Castle Hill.  It’s been suggested that the 4th High Steward, Alexander (1246-1281) was keen to learn the lessons of his father, Walter 3rd High Steward (1204-1246) – after Walter was literally besieged at his other stronghold at Rothesay by a Norse invasion – where the marauders set about hacking their way through the stone walls with their axes for 3 days before Walter was finally forced to succumb to an invasion in 1230.  You can find out what happened to Walter in our blog about his life.  This may well have been the impetus needed to replace their earth and timber Dundonald motte and bailey caput, and which saw this stronghold evolve into what is thought to have been a huge kite-shaped castle with 2 double-D twin towered gatehouses at each acute angle, with other towers probably, although not yet verified, located at the obtuse angles, with a probable curtain wall connecting them all together.  

Model of Alexander’s Castle from Dundonald Castle Museum

The well would’ve been constructed inside the tower because a castle well was built to supply drinking water to the castle, and since castles were built for defence, this shows that they needed their wells to be secure and protected in times of siege – and probably shows us that the High Stewards were not taking any chances after their previous experience!  It was also a sensible move to protect their water supply from deliberate poisoning, and was stationed near what would’ve been the front entrance – which would’ve been heavily guarded day and night.

It likely would’ve had the addition of a stone or wooden cover over it to ensure that animals or people didn’t fall down inside it, and a system of accessing the water where lowered buckets would be filled with water and pulled up. We also might assume that the gatehouse towers were built first, or alongside the well, in order to protect the well as it was being constructed – a feat which may have taken many years and was said to be one of the most expensive parts of castle construction! 

This also allows us to assume that Dundonald must’ve been a place of integral importance if they wanted to go to all this trouble and expense.

Excavations suggest that the eastern gatehouse was partially demolished during the first War of Independence in order to prevent it falling into the hands of Edward I’s army, between 1286 and 1305. It’s thought to have been re-built as a timber and daub fortified structure above the remains of the original stone base. This could have been in part to ensure that the well was secured, for the same reasons as it had been placed there inside the earlier gatehouse.

Well, well, well. So how did they build the well? A well must first of all be deep enough to reach the water table or groundwater beneath the surface – and in this case the water table at Castle Hill it is thought to lie a staggering 30 m down! To add to the mystery, as yet it has only been excavated to about 1.85 m, so we can’t be sure if it ever was a fully fledged water-table-meeting well, or a cistern, which is a fairly shallow underground storage area designed to collect rainwater.  

To build a well these days, it requires either using a hydraulic pump hammer drill which fractures the rock to create the hole or a cable tool, which instead of a rotary motion, pounds the earth and fractures the rock. The only difference is that the medieval well-digger would have been doing all this without the assistance of machinery – literally pounding hammers and backbreaking amounts of shovelling until they reached ground water!  This would’ve been made even more daunting when we consider the poor 13th century workers having to contemplate cutting down though bedrock –  which in this case is made essentially from cooled lava which has become solid quartz-dolerite. This is similar to dolerite, but contains an excess of quartz, which encompasses different sized crystals as an after effect of differing cooling rates of the lava. Quartz-dolerite is commonly found in central Scotland and is widely quarried for road building and is more commonly known as whinstone – which forms the basis for quarrying near Dundonald Castle. However, this answers one mystery since luckily for our medieval well-diggers, quartz-dolerite contains natural fractures which occurred during the cooling period – most likely making it easier to break up than we might first think!  However,  we won’t get carried away thinking this made it easy because it’s consistency means it’s common for large boulders to come loose when its broken up. This would spring another problem for our well-diggers since these huge lumps would then need to be hauled out, and may well break off in a place which could’ve made the intended structure cave in! 

Model of Royal Dundonald Castle showing the position of the well from Dundonald Castle Museum

And what to do with the rock that was removed?  We imagine it might have been used to add to the wall or broken up to become part of the medieval mortar since recent studies have found medieval mortar made of lime, volcanic rocks and halite (rock salt) with a binder of plant origin, consisting of such things as wine, hog’s lard and fig-juice! 

We might take a moment here to sigh and imagine the genius of medieval engineering since this is remarkable given that deep down is unknown territory where the medieval builders could only hazard a guess as to what was down there or how far they would have to dig to reach ground water!

For the well diggers, whose work was probably regarded as a unique and separate skill to the usual tasks of medieval masons, once they had reached ground water, their work was far from done – for now they would need to seal the outside of the big hole they had dug with a casing built from stone in order to stabilise the well,  This would’ve meant that some poor man would have to take himself all the way down inside there – to possibly the depth of 3 buses end to end, if we are assuming this is a fully functioning well.  Adding to the fact that well-diggers often hit caves, which may have needed filled in, there was also the problem of ensuring a sufficient oxygen supply while working inside.  This meant they had to construct a wooden dividing wall built into the well shaft, where any gaps were stuffed with a mixture of pitch and straw to make it as airtight as possible. Seemingly this created a chimney where a fireplace was built beneath that could suck air through the well shaft below. Fresh air then could circulate through the artificial U-shaped pipe with the two halves being separated by the dividing wall, supplying fresh air at the bend.

It may have seemed less of an arduous task, however when we consider that Kyffhausen Castle had a well dug to 176 m,  Königstein Fortress to 152 m and legends tells of one dug down 197 m at Regenstein Castle, all in Germany.  The deepest well in Britain is thought to be at Beeston Castle where the well is 113 m deep!

Beeston Castle Well 

As it stands today, the castle at Dundonald is largely a work of the 14th century, when following his accession to the throne in 1371, Robert II rebuilt parts of Alexander’s castle, chiefly by converting the original North gatehouse into an early form of tower-house.  Few other traces of the earlier 13th century castle can be identified above ground – the well being the only part of it really left after around 780 years, merging with the undulating mounds of grass, which are likely to be the remains of the gatehouse and walls which would have surrounded it. 

The location of the well still remains a mystery in terms of being outside the main walls for the 14th century needs of its residents and its questionable protection for the reasons we’ve discussed. This can only be answered if we assume that the well may have had a well house which could’ve been a defensive structure built around it and possibly guarded. However, this will remain a mystery until there is a full archaeological examination of it in the future. Additionally, we might consider that there is archaeological evidence which indicates that the well was not likely to have been the only source of fresh water…

View from inside Dundonald Castle

There appears to be a rainwater fed cistern – or an area cut from the rock inside the present Castle’s courtyard – which no doubt served as a back-up plan, should access to the well be denied. This cistern was hewn out of the same lava rock where the rain water would probably have passed through sand which collected and filtered the water, perhaps even enriching the water with minerals. However, given that the court yard would’ve been a place of much human and animal activity, its hard to imagine that the cistern would’ve contained as quality drinking water as that which would’ve been found in the well due to  likelihood of seepage from the sewage of livestock or from the residents of the castle themselves! 

We hope that this has helped to answer at least some of the mysteries of Dundonald Castle well!  If not entirely, it has been fascinating to find out about the almost Herculean endeavour which the construction of the well here would’ve entailed!  Indeed the skill to hand-dig through volcanic rock, without the assistance of power tools, is well deserving of our admiration! 

Check out our short video from our YouTube Channel – made by and narrated by our Education Officer, Blythe Paterson who shows more details of the location of the well:

Find out more about:

Well Drilling: https://www.youtube.com/watch?v=0-KLWEnwiaY – Well drilling 101 every step explained by OGB



Ewart, G,  Pringle, D, Caldwell, D, Campbell, E, Driscoll, S, Forsyth, K, Gallagher, D, Holden, T, Hunter, F, Sanderson, D, Thoms, J; 2004. Dundonald Castle Excavation1986-93; Scottish Archeological Journal Vol 26. No 1/2. Edinburgh University Press.

Forbes, D, Murray K. 2012. Dundonald Castle The Official Souvenir Guide. Friends of Dundonald Castle (SCIO31541).


https://www.youtube.com/watch?v=JSM4FlPys8w How do wells work by Concerning Reality




Info-graphic showing comparison of a well and and cistern By תמר הירדני Tamar Hayardeni – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=84942599

Beeston Castle Well by By Nilfanion – Wikimedia UK, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=47646056

Location of the well to barmkin wall: Screenshot from film by Blythe Paterson

Close up of the well: Screenshot from film by Blythe Paterson

Model of Alexander’s Castle from Dundonald Castle Museum photo by Jason Robertson; additional text by Gwen Sinclair for FoDC

View from inside the Castle showing inner and outer courtyard photo by Jason Robertson; additional text by Gwen Sinclair for FoDC

Model of Robert II’s Castle from Dundonald Castle Museum photo by Jason Robertson