Black Mesa is a research centre located in New Mexico(USA). It is the place where the first events of
Half life take place.
It was made on formers nuclear silos in the 50s and transformed into a big scientist research institute. Many secret projects are made here but also researches such as weapons development, teleportation and the world of Xen.
Despite the size of the complex, we know that it is highly protected with security barriers and verifications. The employees live there so Black Mesa contains everything needed for a daily life.
The place is divided in seven sectors and nine levels.The research centre is composed of two groups, the personnel and the employees' families on one hand and the scientist team.
The Black Mesa incident starts during an experience made by
Gordon Freeman, which severely damaged the facility leading to the impossibility of communication with the outside world and the appearance of dimensional holes between Earth and Xen.