Because of the structural support given by the external flying buttresses, more opaque walls were replaced with windows, resulting in the bright interior that distinguished the Gothic style. The use of stained glass to depict story was another way that light was employed in the building of Gothic churches. Stained glass is glass painted or etched with images that sparkle when illuminated from within the church or chapel. Gothic architecture was born in Europe, but it became popular all over the world. There are many Gothic buildings outside of Europe including North America. South America has many Gothic buildings as well. Asia also has some Gothic structures such as the Temple of Heaven in Beijing, China. There are even a few Gothic buildings in Africa such as the Cathedral of Christ the King in Nairobi, Kenya. The name "Gothic" comes from the German word Gotheischutz, which means protection of God. This is because the pointed arch was originally designed to protect churchgoers from their own heavy wooden staves and shields. As time went on this reason for existence began to change though. Churches started to become more opulent and attendees began to be protected from the dark and dreary atmosphere of the church itself. Enter: the flying buttress. The flying buttress is an architectural feature used primarily in Gothic churches to support the nave roof and provide lateral stability without using any iron rods.