America is not a particularly religious country, even though the founding fathers based many of their early documents on religious principles. Nevertheless, there are a number of significant religious sites around the US which can be included in a list like this.
Air Force Academy Chapel* — Near Colorado Springs, CO
Basilica of the National Shrine of the Immaculate Conception* — Washington, DC
California Missions* — San Diego to San Francisco, CA
Christ of the Ozarks* — Eureka Springs, AR
Loretto Chapel* — Santa Fe, NM
Mission San Xavier del Bac* — Tucscon, AZ
National Cathedral* — Washington, DC
St Louis Cathedral* — New Orleans, LA
St Patrick’s Cathedral* — New York, NY
Temple Square* — Salt Lake City, UT.