Marilyn Monroe pretended to marry Joe DiMaggio at Sts. Peter and Paul, in 1954 and took wedding pictures on the steps.
Their actual marriage took place at the City Hall, as the first Mrs. DiMaggio was alive at the time and the Catholic Church is strict about these things. In fact, the first Mrs. DiMaggio did get married to Joe here, which must have stung.
Do what Marilyn could not - go inside. It's beautiful.
Once you are done spend some time in the square and look at the Firefighters Memorial and the statue of Benjamin Franklin.
Use the button below to get directions there, and then pick one of the nearby locations from the list at the bottom of the page. If none of them strike your fancy try changing the drop-down to "All Locations".