Improving my garden for my cat!

Hi!

I’ve got a small back yard and I desperately want to make it more stimulating for my cat. She doesn’t roam the streets as I’m near to a motorway (and cats are a menace to UK wildlife) so her outdoor access is my garden.

I wanted to create some climbing shelves for her on the wall opposite the window. However, the brick work is in bad condition and it’s technically my neighbours wall.

I worry that if I’m to drill into the wall, the brickwork will crumble into pieces! I already periodically get chunks of brick falling off the wall into my garden. Can anyone recommend a way to install shelves onto the wall without drilling directly into the wall? I’m at a loss! Picture of my darling cat attached, sat in her favourite sun spot.