|Libraries||C.V. Starr East Asian Library|
|Vending||2F — Water/Coca-Cola|
|Entrances|| 2F — College Walk (9–5)|
3F — Upper Campus
|Restrooms|| 2F — M/F (business hours only)|
5F — M/F
Kent Hall, home of the MEALAC and EALAC departments, is named after James Kent, Columbia's first law professor. It was originally built to house Columbia's law school, and served that purpose from 1910 to 1960, when the Law School moved across Amsterdam Avenue to the more spacious, yet ugly Jerome Greene Hall. During that time it served as a focal point for the growing movement to admit women to the law school. It was not until 1927 that women were said to have "crossed the threshold of Kent Hall".
Above the doorway is the latin inscription "IVS EST ARS BONI ET AEQUI" - "Law is the art of the good and the just." 
The campus level (3rd Floor) library, now the C.V. Starr East Asian Library, was once the Law Library, and the stained glass window on the east side of the Library is a clear relic of that bygone era.
It has one elevator, which is horrifyingly slow and subject to breaking. On its ground floor, accessible from College Walk, Kent also serves as the home of Student Services and several of its offices, including Student Financial Services, the University Registrar, and the ID Center. The offices seamlessly extend through Kent into Philosophy Hall, which are connected by ground level tunnel.
All tunnels connect to the sub-basement, which is accessed by going down the west staircase all the way to the bottom, turning left, and going through the door. It is missing a knob but it isn't locked so just use your finger to open it. Go to the east end of the basement, and you will see a well-lit, fairly clean corridor. Go north and it will be on your right. "Access route" is painted in a blue stripe on the ground. This continues on to St. Paul's, Avery, and beyond in that direction. This might be legal, but just in case, go at night so you don't run into maintenance. There is a very light security risk.
Go to the Philosophy tunnel, but go south instead. This tunnel goes under 116th street (college walk) and ends up in the basement of Hamilton. It is blocked later on so that is as far as can you go. This might be legal, but just in case, go at night so you don't run into maintenance. There is a very light security risk.
This tunnel used to be the student rifle range. In the basement, go up the random concrete staircase in the middle of the north wall. It is very dark - if you ever wanted to see perfect darkness, this is pretty close. Remember the caver's rule: bring 3 sources of light. Even a cell phone's screen will work in an emergency. I imagine if you dug around down here you might find some bullets. The end of the tunnel reconnects with the Kent tunnel system through the door marked "Organ Pump Room" or something of that nature. You have to get through a small metal hatch to get to that door from the rifle range. That room is full of decades-old machinery and a big defunct pump. The small room at the end holds Sir Lance's rolodex, placed there by the LTV Squad. Bring a pen to sign it.
Students are not permitted on this route. It's very dark, but there's very little risk that security will find you. This tunnel is cool, unlike the ungodly hot one next to it. You need to be a little flexible to get through the small hatch. One of Benoit's tours left tags down here on the pipes. Two people or more is highly recommended.
Climb up the ladder in the NW corner of the basement into the hatch. It's really only a dead-end; there is no exit from Buell. If you were to continue past Buell northwards you would get blocked at a hot mass of pipes, beyond which are connections to Uris Hall, Low Library, and St. Paul's Chapel.
There are no alarms or cameras. This is probably the most physically dangerous passage on campus. You are in a passage that is 5 1/2 feet tall, with scalding-hot water dripping from uninsulated steam pipes all around you. There are no lights, muddy pitted floors, and exposed electrical wires. Not to mention the heat and humidity - it is unbearably hot (>100F) and moist (100%). The air is thick with dust (and probably asbestos too). There is no one to hear your screams if you are hurt. You could rot for years down here without being found. I guarantee that no maintenance person has been here in decades. There is virtually no risk of being caught. However, it's very dangerous, so only go there if you're an experienced tunnel explorer. Go in a group, wear protective clothing, bring multiple sources of light, bring water to drink, and tell people where you're going so they can get help if you don't return.
The attic is easily accessible through the east stairwell. It is dark, spooky, and dirty. There is evidence that people use it as a space for drinking, smoking, and other illicit activity.