In 1893 (the year The Stereoscopic Society was founded) Henty Oakley purchased Dewstow estate in Monmouthshire (https://www.dewstowgardens.co.uk/), and created a wonderful garden containing a grotto constructed by the famous Pulham company of Broxbourne, Hertfordshire. After Oakley’s death in 1940 the gardens were neglected and the grottoes filled in and forgotten. The estate was purchased by the Harris family in 2000, who discovered steps leading underground and re-discovered the amazing grotto. These images were taken in my visit in July 2021 using my Fuji W3 and twin GoPro Hero3 Black cameras. There is more information about the Pulham company and the gardens they worked on in https://pulham.org.uk/.
It’s a wonderful place to explore.