The Royal Swedish Opera on Gustav Adolfs Square has witnessed both a royal assassination and the live debut of "Dancing Queen."

King Gustav III, a theatrically minded monarch who founded the opera in 1773, was shot at a masquerade ball here in 1792. The plot proved so dramatically irresistible that Verdi later turned it into an opera. The king lingered ten days, undone partly by pneumonia after well-meaning courtiers opened the windows.

The present building dates from 1898. On 18 June 1976, the night before King Carl XVI Gustaf's wedding, ABBA premiered "Dancing Queen" at a televised gala here, with the future queen reportedly nearly dancing in the royal box.

VoiceMap's self-guided audio tours pause at the opera to trace Gustav III's fingerprints across Stockholm, from the academies he founded to the bedroom where he died, and to revisit the gala that gave the world its most famous disco moment.