The mosque on Prospect Street is not only Cambridge, Massachusetts,' largest mosque, but it is also the city's only mosque. As many as 1,000 people a week, including immigrants, students, families and residents from surrounding neighborhoods, stop by to pray up to five times a day as Islam requires. Known as the Cambridge mosque, it is run by the Islamic Society of Boston and is just a few short blocks from the well-traveled Red Line, which serves Boston's many universities and colleges. "The mosque is open to everyone," says spokeswoman Nicole Mossalam. "We don't have a core membership. It's very...