Thanks-Giving Square is a public/private park featuring a shell-shaped non-denominational worship room with an incredible series of stained glass skylights.
The square itself could almost be mistaken for any other public plaza, were it not for this odd building in the corner. After walking up a spiral ramp there’s a doorway into the chapel-like space which features a few chairs, an alter that’s a big cube of solid marble, and a piano that’s used for funeral services and such.
It’s free and almost always open to the public.
The park outside is also worth strolling through, though unfortunately part of the water feature was not functioning during my visit to Dallas.