More famous than the house are the stairs. As in the movie, they are right next to the house and are very steep. All long the wall are various Exorcist quotes fans have written over the years.
Here is the university campus where Ellen Burstyn shot the movie-within-a-movie. The path she takes home from the university is actually real, no Hollywood tomfoolery here! (By the way, directly across the street from the Exorcist house is the bar that inspired St. Elmo's Fire.)
Here is the bridge where Ellen Burstyn meets the priest to discuss the exorcism of her daughter.