Kungsgrottan is a small grotto formed by a huge Ice Age rock in the Swedish town of Trollhättan, which is famous for its waterfalls. The Trollhättan waterfalls have been used for hydropower and boat travel since the 19th century and the town is well known for its King Oscar’s Bridge which overlooks the powerful Trollhättan Falls.
Somewhere along the way, Swedish royalty began to memorialize their visits to the town by putting their signature on this large rock which sits just below the bridge. Many visiting monarchs and personages have carved their name into the rock, with the oldest entry dating back to 1754, when King Adolf Fredrik and Queen Louisa Ulrika first started the tradition.
The exact reason why this particular rock was used is unknown, but it became known as the Kungsgrottan soon after, even though it is not even a proper cave or grotto. Today there are over a dozen royal signatures, including that of the current heir to the Swedish throne, Crown Princess Victoria, who left her mark on the Kungsgrottan in 2001. Perhaps the royals chose to carve their names there simply because the spot offers a beautiful view over the waterfalls.
You can find the King’s Cave right before Oscar Bridge, down a small flight of stairs.