 Unity Temple, home of the Unitarian Universalist Congregation of Oak Park, Illinois, is one of Frank Lloyd Wright's most famous works. Wright, who was raised in a Unitarian family, envisioned a radically designed religious space with a monochromatic, poured-in-place concrete exterior and a light-filled interior. After years of deterioration, the National Historic Landmark was named to both Landmark Illinois and the National Trust for Historic Preservation's Endangered Lists. The Unity Temple Restoration Foundation secured needed funding from the Alpha Wood Foundation, the Congregation, and private donors, making a three-year, $25 million restoration possible. Completed in 1908, Wright referred to this pioneering work of early modern architecture as his little jewel box. Fittingly, a major part of the restoration focused on the building's art glass. The glass pieces were cataloged, created, and shipped off-site for restoration. In addition, the team from Harbaugh Architects spent nearly a year developing innovative techniques to repair cracks in the building's plaster interior and concrete exterior. The incorporation of nine geothermal heating and cooling wells provided the temple with air conditioning for the first time in its history, and ADA upgrades and the addition of a catering kitchen helped the congregation more fully utilize the building. Unity Temple reopened for services in June of 2017, and the building once again provides a warm welcome to parishioners, community members, and Frank Lloyd Wright fans from around the world. In July of 2019, Unity Temple was named one of the eight key works by Wright to become a UNESCO World Heritage Site, raising the site to the same international status as Machu Picchu, the Pyramids of Giza, and the Statue of Liberty.