Inside The Great Pyramid
This was news to me and maybe it's new to you.
In or around 1976 musician Paul Horn cut an album of him playing the clarinet inside the Great Pyramid.
A short video about it is here:
https://www.youtube.com/watch?v=DxM_FdNX3B4
And here's the full album:
https://www.youtube.com/watch?v=FzNsJEhoPE0
Doh - that's only a partial album.
Here's a link to the album on sale via Amazon.
https://www.amazon.ca/Inside-Great-Pyramid-Paul-Horn/dp/B0000018Y5
Apparently there's a new version with bonus tracks.