The first science fiction con was held in 1891 at the Royal Albert Hall

Charles Wallace writes, "In 1891 the Royal Albert Hall hosted what may be the first sci-fi convention, centered on the book 'The Coming Race' by our old friend Edward Bulwer-Lytton. The video linked above features a trip to the archives of the Royal Albert Hall by host Brady Haran. Good proto new-age weirdness with through-threads to current neo-nazis. Fun for all!" Read the rest