Inscriptions in rocks, believed to date back to the 18th-century, have been found in historic ponds in Longthorpe.
Samia Merrington, 42, found the inscriptions while clearing the main pond at Holywell Ponds.
She started work on the ponds as part of a restoration project during the pandemic to return the site to its former glory. There are eight ponds at Holywell - supplied by a natural spring - which feed into the main pond.
Mrs Merrington said: “We think that the inscriptions on the stones we found came from a pavilion, which was a few metres from the pond.
"We believe the stones were thrown into the main pond by vandals in the 1800s.”
In 1875, the Peterborough Standard reported that 'youths pulled down a once beautiful Grecian summer-house' and 'broke it's pillars to fragment and threw them into one of the adjacent pools’.
The newspaper also said that the building’s ‘rounded pillars and carved capital could be found beneath the pond’s water’.
“I was removing the litter in the main pond from years of neglect,” Mrs Merrington said. “I started pulling up some stones and then I thought that I could lift some bigger stones.
“During the time I’ve been working here I would always find foundations when I was digging - so I would always speculate as to what they were."
Mrs Merrington said that the group of volunteers at Holywell Ponds - known as the Friends of Holywell - have been working with Peterborough Museum and an identification expert from Cambridge to learn more about the inscriptions and the site’s history.
They are also working with English Heritage to register the main pond as Grade II listed - which is any building or structure listed by the charity of special interest and warranting preservation.
“The pool is a monument and we are trying to grade it,” she said.
“The grotto is already Grade II listed. The museum has sent us documents showing that the pool was an extension of the cave - so logically it should be Grade II listed.
“It would be massive for us as we would receive financial contributions and funds from the government to continue our project.”