In September of 2015, I spent a week in Luxembourg for work. When I was making my plans, I realized that instead of flying home through Charles DeGaulle, I could take the TGV down from Luxembourg, stay a couple of nights in Paris, and then fly home Sunday… for less.
And so my 40 hours in Paris was hatched. I got a cheap 4th floor AirBnB in Le Marais, there was a solid restaurant across the street I had dinner at twice, and had breakfast at the bakery around the corner. I didn’t go see any of the “sights” - I spent 28 hours just walking around, drinking coffee, making photos, and responding to the city.