Did you know this beautiful historic church is right here in Gowanus? I stumbled upon it while exploring - it's on the corner of Sackett and Hoyt Streets (at 433 Sackett St.) and takes up the whole block on Hoyt. Saint Agnes is more than a century old! First built in 1901, it was destroyed by a fire caused by a lightening bolt. Here's a surprisingly detailed account of the fire from the New York Times. It was rebuilt 3 years later in 1904, which is the church you still see today. According to Lost City, "it's the sole surviving creation of Thomas F. Houghton, the son-in-law of Brooklyn's most prolific church builder, Patrick Charles Keely." Saint Agnes is a Roman Catholic church, but all are welcome if you'd like to check out the inside. Take a break from that New York hustle and bustle to meditate and/or pray if you like. Sundays it's open for mass at 9AM (English) and 11:30AM (Spanish). Wednesday and Thursday daily mass is at 8:30AM in English. Saturday's mass is also English and is at 5PM (for those of us who like to sleep in :) That's the one I'll check out.
Hopefully this won't happen to you at St. Agnes, but if it does, it seems like you'll have plenty of room to move around. The church combined parishes (people who go to the churches regularly) with St. Paul nearby in 2011, due to low attendance.