Interrogation is a room in the NCIS Building where various suspects and criminals in various crimes that NCIS teams are investigating are brought to be interrogated, mostly by the NCIS Major Case Response Team led by NCIS Special Agent Leroy Jethro Gibbs.
Numerous suspects in cases concerning dead civilians or deceased personnel attached to the United States Marine Corps or Navy are often brought here so they can be interrogated into giving up their whereabouts at the time the crime was committed or if they are the true person responsible, they can often speak about their crimes, essentially confessing to them.
In the JAG Season 8 episode/NCIS backdoor pilot episode, "Ice Queen", the room was originally composed of a single room with three or four walls with a table in the center of the room with three chairs at the table while a phone sat in the center of the table.
By the time the NCIS Season 1 premiere episode, "Yankee White" aired, the phone and the third chair were both removed, resulting in the table and two chairs being left behind and as such, those items remain in the Interrogation room to this day.
A single glass window is behind the table with the glass hiding the Observation room which is located directly next door while a single camera hangs above the room, flashing every time to reveal that the interrogation is being recorded.
The Season 2 episode, Caught on Tape (episode) revealed that there are two interrogation rooms.
In the Season 3 episode, Bloodbath (episode), it was shown that the TV in the interrogation room is now capable of uploading any kind of photos from a memory stick or a memory card with ease.