hammer head [= hammer head shark]

head to head configuration

head to head structure

arc stair

auxiliary stair

Cantilever Stair

circular stair

corkscrew stair

crane stair

double stair horizontal well

double stepping on one stair

Escape Stair

exterior stair

Fire Escape Stair

fire-escape stair

floor slab with stair steps

halfpace stair

main stair

newel stair