The Omo sebua is a traditional house style from Nias island, Indonesia. They are built only for the houses of village's chiefs. Situated in the centre of a village, omo sebua are built on massive ironwood piles and have towering roofs. Nias culture, with former frequent inter-village warfare, has made the design of omo sebua impregnable to attack. The houses' sole access is through a narrow staircase with a small trap door above. The steeply pitched roofs can reach 16 metres (50 feet) in height. Apart from a strong defense against enemies, omo sebua have proven earthquake resistance.