This is probably a reference to the Mariners' Church in Detroit. The church is located near Cobo Hall, named for Alfred Cobo, the last Republican mayor of Detroit (the city began to go downhill after he left office in 1957). I saw the church when I was in Detroit in 1980 for the Republican National Convention.
yes, I think that is correct. I was in hart plaza in the summer of 2013 with my kids, going to a Tiger game, and we took a walk on the riverfront. Walked past this church on our way to Cobo.
I explained the significance to them...they are 18 and 23 yrs of age, and having been born in michigan, and spending most of their childhood there, they were moved by all of it.