Kasubi Tombs: Kampala City, Uganda

Mutesa I, king of Buganda from 1856 to 1884, was buried in this thatched tomb near Kampala, Uganda, shown here in 1906.

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Thatch -- tightly bundled, overlapping layers of grass, reeds or similar vegetation -- is a time-tested green building material. Cultures throughout the world developed variations of thatched roofs and walls, all of which adapted to the varying climates to accomplish the same goal: keeping inhabitants warm and dry.

Thatch can be created from fast-growing, easily replenished plants, making it a truly renewable building material. It's also an excellent insulator. Many houses with thatch roofs use a simple framework to support the thatch; roofs properly built from this material can fulfill the insulation requirements that several layers of shingles, sub-roofing and roof material do in a modern roof [source: McGhee & Co. Roof Thatchers].

One of the largest and most historic thatch roofs in the world is part of the Kasubi Tombs, near Kampala City in Uganda. Four kings of Buganda are buried within a main tomb at this World Heritage Site. A towering forest of poles supports the giant roof, which shelters not only the tombs but also a one-of-a-kind collection of historic relics. Unfortunately, in March 2010, a fire swept through the main tomb, destroying many of these relics.

The legacy of this massive thatch structure can be seen across the globe. Modern homes -- and rehabbed historic homes -- are being rebuilt with thatch roofs, which can last for 60 years when properly constructed [source: McGhee & Co. Roof Thatchers]. And thanks to modern fire-retardant technology, the chance of fire destroying these green roofs is significantly reduced.