The big cat tree we just bought is the first scratching post that Sammy has
ever been able to stretch upwards on.  She likes to scratch on sisal but
every scratching post in the house is about 3 feet too short for her to
stretch fully, vertically.  The sisal post on the new tree, however, goes
all the way to the top (just the post itself is almost 5 feet tall).

http://www.possibleplaces.com/catnipped/nipped/tn100_0735.jpg

Last night I watched as she scratched and stretched horizontally on the very
bottom of it (like she has to do on the one in my bedroom), then she
slooooooooooooowly placed her right front paw a little bit higher, then
sloooooooooooowly placed the left front paw a little higher,  then she kept
"walking" her front paws up the sisal post in seeming amazement that she
could do this.  When she had stretched as far as she could, vertically (look
at the picture and imagine her front paws halfway between the highest
"hammock" and the house on top), she sloooooooooowly raised her right hind
paw and put it on the post, then she slooooooooooowly placed her left hind
paw on the post.  She was *totally* amazed that the whole structure didn't
tip over on her (actually, given Sammy's size, so was *I*).  She proceeded
to very slowly climb the post until she could peek into the house to make
sure nobody else was in there, then she crawled over the ledge, shoved her
entire body into the house (picture a 20 pound ham in a 2 pound sack),
turned around inside (!!!!!) so she could face outward.  She is so big that
quite a bit of her was sticking out the front of the house, but she looked
*quite* smug at her accomplishment!  ;>

You have to remember that Sammy *NEVER* jumps up on anything higher than my
bed.  Aside from most everything tipping over from her weight, there's the
danger of jumping with that much weight *down* from wherever she is.  So, I
don't know if she'll ever repeat this performance, and there I was *without*
my camcorder!!!  :<