In Paris you can walk along the Promenade Plantée, or the Coulée verte as it is called now. This used to be an old railway, but when it was discontinued, they made an absolutely gorgeous path here to walk. (This was the inspiration for the High Line in New York).
The coulée verte is 4.5 kilometres long and the railway is 10 metres above the street. Under the railway you now have all kinds of artisan shops and workshops. There are several places where you can exit the coulée verte or begin your walk. There are als lots of benches and there is even a park in the middle.
Take the metro to station Bastille, take exit nr 4 and then it is just a few minute walk. It is a wonderful part of Paris and I loved walking here. Especially since there are not a lot of tourists here :-)