Which sentence states a fact?

 - Willis Tower ruins the beauty of Chicago's downtown.
 - Chicago's Willis Tower stands 1,450 feet tall.
The second sentence states a fact.
Chicago's Willis Tower stands 1,450 feet tall.
It can be proved by checking a website about Willis Tower.
The first sentence states an opinion.
Willis Tower ruins the beauty of Chicago's downtown.
Ruins the beauty shows what a person believes, thinks, or feels. Another person might have a different opinion about whether Willis Tower makes Chicago less beautiful.