Haven't put up the artificial tree for several years now but when we did it was secured upright by wires to the woodwork and heavy bookcases. The cats did climb but the tree didn't fall...And..no lights, but all the colorful ornaments were made out of cloth or painted wood. The little stuffed birds inevitably had kitty flying lessons by the time New Years rolled around but they don't break. Garlands went up but were taken down if anyone was naughty. The cats were pretty good for most of December though. Many years ago we had an "incident" with tinsel with one cat and his miracle digestive tract and a close call with another cat who had a penchant for putting those little tree lightbulbs in her mouth.
