Steel is one, plus skyscrapers.
The Vikings, the guys who raided and pillaged much of
Northern Europe, were successful because they are amazing shipbuilders. The
Vikings invented the longship, a graceful, long and narrow, but lightweight wooden
boat more often used for troop transports. The longships were very seaworthy
ships, and it possessed a shallow draft enabling the ship to be sailed into
rivers or beached into beaches so Viking troops can easily do amphibious
landings on seaside towns or plunder more inland towns.
Where is the pictures or sum ?