List of top Minecraft Adventure servers, if you're bored of classic Minecraft servers be sure to check out Adventure servers!
What are Adventure servers?
Unlike classic gamemodes like Survival and Creative, Adventure gamemode is intended for servers and maps created by players. Most of Minecraft Adventure servers would limit some Minecraft features and force players to play by the rules or complete specific challenges.
On some Adventure servers players can't break specific blocks but can still interact with other players and mobs, while on others you can mine blocks but you still have to follow the storyline, but that's really up to each Minecraft servers since most of Adventure servers are unique.
Minecraft Adventure maps?
Minecraft Adventure servers generally always use custom maps for Adventure Mode, and many custom Minecraft maps are set to this game mode; players cannot break blocks or place them, therefore disallowing them to destroy the map, or add anything to it that would ruin the map or gameplay on Adventure server.
Adventure is also often used to protect various multiplayer servers from griefers and such. Sometimes command blocks are used in conjunction with Adventure gamemode, in servers and custom maps.