Architecture is a technology in Age of Empires II that can be researched at the University once the Imperial Age is reached. Once researched, it strengthens buildings by providing +10% hit points, +1 armor, +1 pierce armor, and +3 building armor. Note that building armor doesn't protect against all kinds of bonus damage against buildings, it reduces the bonus damage from siege weapons, ships, Villagers, Tarkans, War Elephants, and Camels, but not from infantry or archers.