Situated slightly to the north of the City Observatory complex is a hidden burial chamber that dates back to the late 18th century and has been shrouded in secrecy ever since.
The crypt, which is believed to be the first Jewish grave site in Edinburgh, was created for a Mr Herman Lyon, a wealthy Jewish man who arrived with his family in the capital from Prussia in 1788.
In 1791, Mr Lyon appealed to the town council for a burial site for himself and his wife, stating that they did not wish to be interred in a Christian cemetery. Eventually, they agreed on a plot of land atop Calton Hill, which was sold to Mr Lyon for the princely sum of £17 sterling.
READ MORE: The prison-like Edinburgh estate whose architect 'should have got the jail'
It's understood that Mr Lyon's tomb was built within an existing natural cave or fissure, which appeared in local legend as the place where a Leith 'fairy boy' was spotted dancing with the fair folk.
Following a series of drainage works around the site, the Calton Hill mausoleum had its entrance concealed and was very quickly forgotten about. It did not appear on any city maps bar from one 1850s Ordnance Survey map.
The Georgian tomb lay dormant and untouched for the best part of two centuries until two local men stumbled upon it after climbing through a rabbit hole and into the main chamber.
In August 2013, a full standing building survey was carried out by the AOC Archaeology Group, who identified the main chamber with its barrel-vaulted roof. The floor was covered in a deposit of modern hardcore, which experts presume was dumped there during the construction of the adjacent tarmac road.
Sign up to our Edinburgh Live nostalgia newsletters for more local history and heritage content straight to your inbox
The Lyon Mausoleum has been found to measure three metres by four metres, with a 12-metre-long passageway leading up to the crypt.
The entrance remains completely sealed off to the public. However, if you're ever walking in the area, have a look out for a set of slabs around the north-western edge of the City Observatory. These are understood to be the roof of the burial chamber.
Very little is known about Mr Herman Lyon or his wife, other than the fact that he made his money as a "corn operator" - which had nothing to do with farming. This archaic term was actually used to describe someone who worked in the field of chiropody.
Lyon practised both as a chiropodist and dentist in the Canongate and must have been quite successful given that he was able to fund a private mausoleum for himself and his family on such a prominent site.
Further information on the Herman Lyon Mausoleum can be found on the Canmore website.
READ NEXT:
Fascinating story behind Edinburgh's 'Canny Man's' and how unofficial name stuck
Beach near Edinburgh where you can stumble upon wrecked WWII submarines
Edinburgh's trouble-hit former Hibs pub that now bans football colours on match days
Edinburgh's lost 'bendy bridge' that locals either loved or loathed
The working class Edinburgh pubs that have been gentrified beyond recognition
