Where were Pokémon Gold and Silver first publicly showcased?

Pokémon Gold and Silver were first publicly showcased at Nintendo Space World.

The games appeared at the November 1997 Nintendo Space World expo in Japan. The presentation showed that the follow-up to Pokémon Red and Green would be more than a minor update, promising a new world, new species, and a larger adventure.

Development continued for several years because Game Freak also worked on projects including Pokémon Stadium and the localization of the first generation. Gold and Silver eventually launched in Japan in November 1999.

Nintendo Space World was a major showcase event for Nintendo hardware and software. A later Space World 1999 demo of Gold and Silver became notable for revealing early versions of Pokémon and features that did not appear in the final games.