Religious or not, the Notre-Dame Basilica is a sight to see. It's beautiful enough to stir feelings of awe and admiration even for me.
I had a strange fixation with the prayer candles that decorated the aisles of the basilica. For a dollar or two you could make an offering, say a prayer, and light a candle. Some where small and multicoloured, others long and I suppose more pious, for their offerings were more expensive than the small candles, and they burn for four days rather than four hours.
Truly, an excellent place to sit, ponder, and pray.