There are twelve barracks. Two situated behind every tier three tower. There are two types of barracks, the ranged barracks and the melee barracks. When your melee barracks in a lane is destroyed, your opponent’s melee creeps spawn stronger and give less gold and experience when killed. The same is true for the ranged barracks and ranged creeps.
Barracks can only be attacked if the tier three tower guarding it falls. Barracks also have a sight range of 900 during the day, and 600 at night. They do not have true sight like towers, but do have backdoor protection.
Unlike towers, barracks will slowly regenerate health.
Each base has their own fountain which is used to heal, and regain the mana of heroes. It is also where every hero spawns in a game, and returns too when it dies(most of the time, anyway). It is also the location of the base store where most of the items in the game can be bought for your hero.
The Dire fountain can be found on the extreme top right hand corner of the map, and the Radiant fountain on the extreme bottom left.
Ancients are the two large structures found in the middle of each base.
In order to win a game of Dota, you must destroy the opposing team’s ancient before they destroy yours. The ancient will be invulnerable until the two tier four towers defending it are destroyed.
Ancients, like barracks, will also regenerate health—but at a slightly higher rate, and have backdoor protection. They also have a 1800/1800(night/day) vision and a true sight range of 900.
You may also see other small buildings like the ones shown in the image below, but these serve only as buffer between the barracks and the tier four towers, and creeps will attack these first before hitting the towers. They also give quite a bit of gold, are weak, and have no offensive capabilities whatsoever. Although they do have backdoor protection.
These buildings have no shortage of names. They can be known by the building names used in DotA, which are Moon Well(or well) if on the Radiant side or Ziggurat( or Ziggu) if on the Dire side. They are also known as huts, pillars, or shrines.
However since there
is no official name for them—the game simply naming them “Building”, it’s really up to you what to call them. However these buildings are generally so insignificant that you don’t even need to know the name of them.