What is the largest arena in college basketball?

The largest actual Basketball arena (one specifically built for basketball) in the US, collegiate or professional, is Rupp Arena, where the University of Kentucky basketball team plays, and which has an official seating capacity of 23,500.

http://en.wikipedia.org/wiki/Rupp_Arena

The Carrier Dome, where the University of Syracuse's football, basketball, and lacrosse teams play, and which has a listed seating capacity of 33,000.

http://en.wikipedia.org/wiki/Carrier_Dome

The largest NBA arena is the Palace at Auburn Hills, where the Detroit Pistons play, and which has a seating capacity of 22,076.

http://en.wikipedia.org/wiki/The_Palace_of_Auburn_Hills