sentences:  Lu's most widely publicized work involves his discovery of the girih tiles, a set of fundamental geometric tiles used to create a wide range of patterns in medieval Islamic architecture.In collaboration with Paul Steinhardt, he demonstrated their use to create quasicrystal tilings on the walls of Darb-i Imam shrine (1453 A.D.) in Isfahan, Iran.The finding was considered a significant breakthrough by demonstrating a simple and straightforward method that could have been used by common workers to create extremely complicated patterns using girih tiles, and by identifying a medieval example of quasicrystalline patterns, which were not widely known to or understood by the West until the discovery of Penrose tilings by Roger Penrose in the 1970s.