Ellie Cawthorne: Your new book chronicles your hands-on work on some of Britain’s most significant stone structures. What has that work involved, and why did it inspire you to write a book?

Andrew Ziminski: Over the course of my career as a stonemason, I’ve worked across the scope and spectrum of history. From parish churches to Georgian townhouses, Roman baths and medieval cathedrals, I’ve worked on all sorts of buildings, spanning 2,000 years of history.

When restoring or conserving historic structures, my main concern is to discover why a building has started to fail. Then it’s a case of cutting out and replacing anything that’s decaying, while maintaining as much of the original fabric as possible. You could say that stonemasonry is basically a case of large-scale dentistry. But it’s not just about cutting and fixing stones. One of the most fascinating aspects of my job is observing the different environment, landscape and cast of characters that every single building comes with.

Working people don’t tend to write books, do they? They certainly don’t write history books, and that’s something that motivated me to record my impressions and offer another perspective on how people have managed materials to create some extraordinary structures.

How much have the stonemason’s methods changed over time?

Since I spend every day absorbed in the past, my work can’t help but be coloured by the old way of doing things: how people used tools and materials, how they looked at a building and put a structure together.

The tools I use on a daily basis have changed very little since Greek times. In fact, I was at the Pitt Rivers Museum not so long ago and they’ve got a 4,500-year-old wooden mallet in there that is almost identical to the one I use. If you look at the surface of the stones at the Roman baths in Bath, you can see that it has been finished in the way we would still do it today. And the tools that they used to lift massive blocks of stone, called lewis pins, they’re exactly the same as the ones we still use. I do use power tools, but if there was a solar flare next week and all the power cut out, I could happily carry on in the old ways.

A Gorgon's head carving at Bath's Roman baths
This Gorgon's head carving at Bath's Roman baths represents a synthesis of Celtic and Roman styles, says Andrew Ziminksi. (Photo by DeAgostini/Getty Images)

Which era’s capabilities with stone do you find the most astounding, considering the tools they were working with?

The finishing of the stonework at Stonehenge is not just mind-boggling, it’s a Gordian Knot of bogglingness. It’s absolutely insane how the Neolithic builders managed to finish the upright stones, never mind transport them. There’s one stone in particular, stone 56, which has an extraordinarily flat plane across its face. To think that that was created just using mauls – basically big circular stone nodes, some the size of cricket balls, others the size of medicine balls – is absolutely extraordinary.

It’s true that there are other Bronze Age and Neolithic monuments of greater magnitude, like the Carnac stone rows and stone circles in the Orkneys. But there’s nothing else from that time that’s been designed with architecture in mind. Stonehenge was built with details such as mortice and tenon joints to hold it all together. It’s supremely sophisticated – and it actually fits! The lintels are tongue-grooved at each end to hold them in place. That’s an unnecessary extra piece of work to my mind, because these things weigh 20 tonnes each, they’re not going to fall off lightly. What’s interesting is that mortice and tenon joints and tongue-grooved joints are carpentry joints, aren’t they? So there was clearly a carpenter’s ethic at work at Stonehenge.

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In the book you describe making your own Stonehenge-esque monolith using Neolithic methods. How was that experience?

Tedious. Really tedious. All that pounding away! Sarsen stone, the main ingredient that Stonehenge is made from, is super hard. It’s also got a very undulating face, riddled with pock-marks and holes. To turn that material into a perfectly flat plane using just mauls absolutely beggars belief. They must have just pounded and pounded away endlessly. The sarsen sandstone is so unforgiving that it can’t possibly have been just three or four people at work, but hundreds and hundreds. It must have been a huge community effort. The social structure required to achieve that work must have been immense.

Of course, the great puzzle is: why was Stonehenge built? I'll leave that one to academics. What I really want to know is what happened to the builders of Stonehenge after they put the last lintel on? Why did that sophisticated design capability just disappear, or why was it not matched or copied anywhere else? Why are there not Stonehenges all over the place?

One answer could lie in the fact that they would have been creating enormous amounts of silica sand and would have been breathing it in the whole time. As masons, one of the things we always look out for is the risk of silicosis. We wear full-on masks, but obviously they didn’t have those in the Neolithic era. So they would have been dying of this condition fairly soon after conclusion of their task.

Historically, was stonemasonry a respected trade?

There were different layers of acceptability within the trade. Labourers were at the bottom of the pile, mixing the mortar and transporting it up onto the scaffold. Next would be the fixers, with the carvers just above them in the workshop. At the top of the tree would be the sculptors and, at the pinnacle, the master masons. For much of history there were no architects, so masters were the geniuses who came up with extraordinary feats of engineering. Although most master masons are unrecorded by the bishops who commissioned the work, they could earn a great deal of money and were in real demand.

Just thinking about the stonework that has been lost or destroyed as a consequence of the Reformation and the dissolution of the monasteries makes me feel jumpy

Of course, masons fared better in some periods than others. The medieval period saw several building booms, such as after the Black Death, when all of a sudden people had more disposable cash, and were bequeathing money to build churches. Things were a lot harder after the Civil War, for example, when craftspeople were laid off and people began building small chapels rather than large churches. And of course there was the Reformation and the dissolution of the monasteries. Just thinking about the stonework that has been lost or destroyed as a consequence of that… gosh, it makes me feel jumpy.

How has Britain’s architecture been influenced by other cultures?

Every single day that I work in a church, whether a simple country chapel or a grand cathedral, I can see the hand of Islam at work. Its influence can be seen in everything from window tracery to flying buttresses. Take the squinches that support the spire at Salisbury Cathedral. A squinch is basically an arch built into a corner, which is a purely Islamic piece of engineering. Just look at St Paul’s Cathedral. Christopher Wren was a great fan of what he called “Saracenic architecture”. I don’t know about you, but when I look at St Paul’s, I see a dome and two minarets out the front. Even though it’s an English baroque building, it’s about as Islamic a structure as you get.

And this mix of cultures can be seen even further back. Another career highlight for me was working on the famous pediment of the temple to Sulis Minerva in Bath. The central deity is quite simply not of this world. It’s a Gorgon with serpents emerging from its flaming hair. But the way the face stares out at you with its beetle brow and intense frontal gaze is very Celtic. It’s a strange conflation of two cultures, two worlds coming together. Sulis was indeed the local Celtic deity. It’d be great to go back to Bath in the Roman era and see how they constructed the temple. I’d be fascinated to see the interaction between the Celts and the Romans in building what is basically a structure from the heart of Rome, right on the fringes of empire.

Working with monuments like this gives you a real sense of the breadth of peoples involved in the building of Britain. Everywhere you go, you see that foreign people had a role to play, which is something I was very keen to convey in my book.

What kind of things do you uncover when you begin peeling back the layers of a building?

It’s really common to find objects hidden within the structures of buildings. Skulls of farm animals, coins, bits of clay pipe, candle holders, tons of pins. I could go on. One place we worked on had a load of broken 17th-century or 18th-century bottles hanging by their necks in a row from one of the beams in the roof. That was a bit sinister.

Then there was a timber-frame house on the edge of the Savernake Forest we worked on. The people who had lived there over the centuries clearly believed they were being assailed by evil spirits. There was graffiti all around the doors and everything we lifted had something strange underneath – a shoe, tiny shells and a cat under the hearth.

If you could encourage everyone to seek out three examples of exceptional stonework in Britain, what would you recommend?

Go to Stonehenge on the evening of the midsummer solstice. If you cast an eye along the flat plane of stone 56 as the sun goes down, you will see it set on an outlying marker stone. At Stonehenge, the sunset is just as important as the sunrise. So I’d nominate that just for the fact that the builders managed to raise a 30-tonne or 40-tonne stone into position in order for it to act as a sort of astronomical instrument. And it is still doing an absolutely spot-on job today.

Next, I’d nominate the perpendicular vaulted roof at Sherborne Abbey, for its bravado and sheer boldness. It’s one of the wonders of Britain really, equal to anything created in Europe at the time. What is so mind-bending about this fan vaulting is that it was constructed as a consequence of a fire that had ravaged the former roof. The original Norman vaulting collapsed, so they reconstructed it in the latest style. The master mason integrated the new perpendicular work into old Norman structures absolutely perfectly. When you see how flawlessly it fits together from the top, it leaves you completely lost.

Finally, I’d head for Southwell Minster to admire the 13th-century ecological carving. The stonework in the chapterhouse there is beyond compare. The masons would go out to the field, collect tree leaves and copy them. Carving foliage is really difficult, because bits fall off. But the copy carving of the leaves at Southwell is absolutely stupendous. It lifts the spirits when you go there, it makes you happy to be alive.

Andrew Ziminski is the author of The Stonemason: A History of Building Britain (John Murray, 336 pages, £20)

This article was first published in the March 2020 edition of BBC History Magazine