The biggest update in Pokemon Go's history is coming - here are the details

Niantic LabsPokémon Go is finally getting a long-awaited revamp of its gym system, including "Raid Battles" for defeating ultra-powerful Pokémon with other players.

The game's creator, Niantic Labs, detailed what it calls the "biggest update" in Pokémon Go's history on Monday ahead of its first real-world event in July, where around 20,000 players are expected to gather in downtown Chicago.

Most of the changes will be gradually made available in Pokémon Go over the next several weeks, and all gyms are shutting down in the meantime. The redesign should make gyms more accessible and fun to use - and it paves the way for rare Legendary Pokémon appearing down the road.

Here's everything you need to know about the biggest update in Pokémon Go's history: