Evidence Garage is a garage in NCIS where most of the evidence that numerous NCIS teams include the Major Case Response Team led by NCIS Special Agent Leroy Jethro Gibbs is brought back to be processed by Forensic Scientist Abigail Sciuto and later Kasie Hines with the two often being seen in the garage, going through various evidence.
It's also where the NCIS Major Case Response Team Truck and Medical Examiner's vans are also stored when not in use and it's also presumably the same place that the teams depart from once they have received a call about a body being found.
In addition, the garage can also be accessed by an elevator/lift which can be unlocked by a team member's iris or eye.