Beta Theta Pi, Phi Delta Theta, Alpha Delta Phi, Delta Zeta and Delta Sigma Pi are all in Oxford, OH.
The reason why there are so many in Indy., so I have been told, is because it is a very central location within the U.S. and easy access for the Easterners and Westerners to meet (back in the day).

This is a front picture of the Beta Headquarters. It is on 8 acres of land, with a gigantic pond (Stocked with Trout) and then in the back, is our Hall of Chapters with walkways of engraved bricks of individual members and chapters.