Purple Martins

We live in a small town (village) with a population of about 5,000 people, and I was wondering if it is possible to attract purple martins in town.  I am rather centered in tonwn and have a fairly wide open area, with many electric wires for perching, to errect a martin house, but wanted to be sure that it was possible before I went to the expense of trying something that maybe wasn't even possible.  Also, about a mile east of town, a mile south (at a college campus), and a half mile west of town are the closest ponds.  What is your expert advice for me, and if it is possible, how high should it be?  I have read everything from 12 ft. to 30 ft.
Jack