The Lion House, situated on the original campus of the Bronx Zoo, was in need of a critical, yet sensitive renovation. The historical significance of the enclosure needed to be maintained, whilst bringing the building in line with the current accepted standards for the exhibition of animals. The architect decided to pull back the copper roof and open the building and exhibit to natural light. The Texlon ETFE roofing system was utilized to achieve a level of UV transmittance that could not be accomplished with traditional cladding materials.