Are there any tricks to attracting purple martins?

My Daddy would put out egg shells crumbled on a board and they loved that. He also would try and get rid of the sparrows around. He cleaned out the houses really well after each season. If you ever do attract them they come back to the same place every year. They like water close by because they eat mosquitoes. Hope that helps!

Purple Martins prefer housing that is placed in open areas with clear flyways. Choose the center of the largest open spot available, about 30-120 feet from human housing and at least 40-60 feet from trees.

We put the house more than 50 feet from trees and 200 feet from human housing. We have plenty of bugs and have had the Martin house for 4 years now and no takers. I even put a fake bird on the house the 2nd year. Still no luck.

any suggestions are appreciated