You know, cats are not very smart. One of our 13-year-old kitties just got on the roof of our house (there's access from a second-floor balcony where we sit in the evenings sometimes). Of course, it's always easier to climb up than it is to get down, so once at the top she decided she was stuck. Given that the evening light was quickly fading, I decided that immediate action was required, so I retrieved our tallest ladder from the garage and hied myself up to the rooftop.
No cat to be seen.
After a few moments she emerged from the crepuscular gloom so I snatched her up and crab-walked down the roof to the ladder. It was a bit of a challenge to negotiate the transfer from roof to ladder with a squirming feline in one hand, but we all lived to tell the tale.
Needless to say, this particular cat will not be allowed to venture out onto the balcony again anytime soon. :)