I have a bit the same problem...! I moved to an apartment on the 1st floor, and I don't have a balcony. My cats were used to live in a house with a big garden. The house next to mine has a flat roof, so I let them jump out of the window to go outside. The problem was that they couldn't jump back inside (which I didn't know at first). And one of my 2 cats fell down to the ground floor...! Now my neighbours have put a small table on their roof, so my cats can jump back inside! But the one that fell down didn't dare to jump anymore ... And now, when my other cat is outside, Kitty lays at the window, and I feel sooooo guilty 'cause she can't go outside anymore :'( I am trying to mke her a bridge though! :-)