Stained glass has enhanced buildings since the Middle Ages and continues to captivate architects and design lovers today. Used as windows or ceilings, the works, which are constructed of colored glass pieces connected and outlined by strips of lead, are frequently found in religious buildings, such as cathedrals and mosques, although they also became popular for secular spaces beginning in the 19th century and now adorn private homes, hotels, cultural buildings, and department stores. From a Gothic chapel in Paris to a hotel in Mexico City, take a look at some of the most beautiful stained-glass windows in the world and see how architects such as Philip Johnson, Oscar Niemeyer, and Antoni Gaudí have used the art form in some of their most iconic designs.