The Romans were remarkable engineers, thousands of years ahead of us in everything from underfloor heating to plumbing. But even they had their bad days and made mistakes, as a new discovery shows.

Two wells built in the first century AD have been found in a field in Cambridgeshire by archaeologists from the Mola Museum (Museum of London Archaeology), revealing the trials and errors involved in their complex planning and construction.

One of the wells was lined with wooden boards and another contained a ladder. Both are “astonishingly well preserved” after almost 2,000 years of water soaking.

The wells were dug to a depth equivalent to the height of an average modern two-story house. However, the first well did not go quite to plan and collapsed shortly before completion because its walls were not properly secured. The ladder they had been using was buried in that well when it collapsed.

The Roman builders had to go back to their drawing board before working on another well about 20 metres away. This time they learned from their mistake and lined the new well with wood in an impressive feat of engineering.

Simon Markus, project manager, told the observer: “It would definitely have been very upsetting to lose that much work. The fact that the ladder was in the well suggests that they were still working on the well at the time of the collapse. They were about 8.5 meters deep, so they were close to completing the excavation.”

He added: “As we discovered right from the start of our excavations, the clay literally separates from the firmer earth and rock. We’ve all done a bit of DIY that didn’t quite go to plan, but this was a failure of Roman engineering on an industrial scale. It would have taken a lot of effort to dig this well, which they then had to abandon completely.”

He spoke of the grueling excavations involved: “The tools they used back then were obviously very different to ours. The geology is quite solid, so it was a laborious process. Just seeing that work disappear almost instantly must have been a huge annoyance for them.”

The wells belong to a settlement that stretched from the Iron Age to the Roman period and became a centre of industrial activity between 43 and 150 AD. There is evidence that Romano-British metalworking, carpentry and woodworking took place within a large, enclosed site.

The residents had obviously dug a well because they needed access to a water supply.

Some of the larger preserved pieces of wood even show decorations, including horizontal lines, that may provide a clue as to what was made in this ancient settlement.

Archaeologists believe that the Romans reused old furniture as building material, as they were unlikely to have decorated wood that no one would ever see at the bottom of a well.

The amount of waste wood discovered in the second well, which was later used as a landfill, indicates a significant industry. The contents are being carefully examined by specialists.

At the bottom of the well, archaeologists also discovered an area covered with cobblestones, which would have helped filter out the mud as the water rose from the ground, providing the Romans with a slightly cleaner water source.

Mola archaeologists have also found evidence of a probable Roman road near the site, suggesting that the workshop was part of a larger trading network.