... it's actually a cross on a hill near Santa Fe, NM.
I've been able to find only only town in the U.S. beginning with X: Xenia, Ohio. Figures it would have to be a state that has no mountains. Well, there are hills, so there is hope.
Xavier University, Cincinnati, OH
Xavier University of Louisiana
any other "X" schools
Xalapa Enriquez, Mexico (Veracruz)
Other possibilities? Anyone?