The building that must be destroyed to win a Dota 2 match is the Ancient.
Each team has an Ancient inside its base, and destroying the opponent’s Ancient immediately ends the game. The two structures are commonly associated with the Radiant and Dire factions, whose bases sit on opposite sides of the map.
Reaching the Ancient is difficult because teams must first fight through lanes protected by towers, barracks, creeps, and defending heroes. Destroying enemy towers opens the route into the base, while eliminating barracks makes that lane’s enemy creeps weaker and allied creeps stronger. Even after entering the base, attackers must coordinate carefully because the Ancient is heavily defended.
Players sometimes confuse the Ancient with a Nexus or a Throne, terms used by other multiplayer online battle arena games. “Core” can also be used informally to describe a team’s main objective, but the canonical Dota 2 name is Ancient. The word also appears in the game’s title history: Dota began as Defense of the Ancients, the Warcraft III mod that inspired Dota 2.