The Omo sebua is a traditional house style of the Nias people from Nias island, Indonesia. They are built only for the houses of the village's chiefs. Situated in the centre of a village, omo sebuas are built on massive ironwood piles and have towering roofs. Nias culture, with its 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 defence against enemies, omo sebua has proven earthquake resistance.