My office is Doherty Hall 4302D, in the back of the philosophy grad office suite in DH 4301. Doherty is a strange building, so my office can be difficult to find. In general: if you end up in the Chemical Engineering 4200 offices, go down to the second floor, walk to the other side of the building, then go up again.
If you come into Doherty from the east (front entrance by the painted fence): continue down the hallway, go left at the end, then go right up one flight of stairs. Continue walking toward the back of the building. There will be a second flight of stairs down the hall, and two elevators to the right of the stairs. (Don't take the elevator against the wall at the end of the hallway.)
If you take the stairs, go up two flights. At the top, go through the door held open by the "philosophy stone." The door to the 4301 suite is immediately to your left. Alternatively, taking the left of the two elevators to the 4th floor will let you out in the 4301 suite. My office is at the end of the hall past the kitchen.
If you come into Doherty from the south (ie, through the door across from Baker Hall): there's a stairwell right in front of you after you walk in, and two elevators directly behind that. Take either the stairs up three flights, or the left of the two elevators to the 4th floor, and follow the directions above.
If you come into Doherty from Wean Hall: this changes depending on what floor you're on. Take the first flight of stairs you see, or the non-freight elevator closest to Wean, to the 4th floor.