In 2004, the Methuselah Foundation began a donor initiative called "The Methuselah 300" ("The 300"), a community of philanthropic donors pledging $25,000 over 25 years, at a minimum of $1,000 annually, toward the organization. The initiative was named after the 300 Spartans who held the pass at Thermopylae in 480 BC during the Greco-Persian War. In addition, in 2015, the foundation began memorializing The 300 donors with a monument at St. Thomas Island in the U.S. Virgin Islands.