2 ms·
... including ordinary stairs: e.g., http://en.wikipedia.org/wiki/Natural_History_Museum_%28Ireland%29#Stairway_collapse http://en.wikipedia.org/wiki/Natural_Hi
by gjm11 16y ago
... including ordinary stairs: e.g., http://en.wikipedia.org/wiki/Natural_History_Museum_%28Ireland%29#Stairway_collapse http://en.wikipedia.org/wiki/Natural_History_Museum_%28Irela... .