More than 250 years ago, the decorated planks covered the "shell grotto" at Newhailes House in Musselburgh.
They have now been returned there for the first time in a decade so that conservationists from the National Trust for Scotland can work towards putting them on display. They hope the move will help visitors discover how spectacular the gardens once were.
The planks, decorated with shells and sparkling pieces of industrial waste, were found by archeologists in a burn close to the grotto in 2001. They had originally been mounted on the walls of the grotto some time between 1721 and 1751. After a decade of being kept at the NTS conservation studio at Hopetoun House, they have now been returned to Newhailes, thanks to the creation of a special archeological finds store in the house's stables.
The creation of the store, which will also contain archeological finds from other Trust sites, means that the planks can be kept in temperature and humidity-controlled conditions as conservationists work out how best to preserve them.
Trust archeologist Daniel Rhodes said that the shell grotto, which stands by a pool and waterfall, was originally part of a formal walking route around the gardens.
"As part of the estate walk you'd stand on the opposite side of the pool. There's a small waterfall and then there's this highly reflective shell grotto. Two torches mounted either side of the doorway would reflect in the pool and the shells. It's part of the entire designed landscape," he said.
Mr Rhodes said it would be some time before the decorated planks could be displayed to the public, but they would help visitors to appreciate the lost garden. "They're very complicated items to conserve because they're made up of four different types of material that all need conserving.
"Being able to show them to the public will allow us to give people a clue as to just how spectacular this estate once was. It's really important to the Trust," he said.
DIGGING INTO THE PAST
NEWHAILES House was built in 1686 and bought by the Dalrymple family in 1707, who owned it for 200 years.
In 1997 it was bought by the National Trust for Scotland with the aim of preserving the building. But when the estate was examined, the remains of a 250-year-old formal landscaped garden were discovered beneath the undergrowth.
As well as the shell grotto, the garden featured a raised causeway with commanding views. It also had the only tea-house in Britain to have been built over a burn.
It was thought that all the shells from the grotto had disappeared until they were uncovered by archeologists in 2001.