"The Lost Century: And How to Reclaim It" is a 2023 documentary directed by Michael Mazzola and presented by Dr. Steven Greer. It explores a century of illegal UFO secrecy that, according to the film, has cost humanity hundreds of years of spiritual, cultural, and technological development. The documentary exposes the impact of this coverup on the planet and humanity and discusses ways to reclaim control of our collective destiny. It features stories about suppressed inventions capable of producing vast amounts of energy cheaply and cleanly, and critiques not only fossil fuel industries but also solar and wind energy sectors as insufficient solutions. The film also touches on governmental revelations about UFOs and extraterrestrial technology, suggesting a potential for a revolutionary future

. In a different context, "The Lost Century" can also refer to a historical or religious concept, notably a claim by Herbert W. Armstrong about a "lost century" in early Christian church history (50 AD to 150 AD), during which records were allegedly suppressed, leading to a break between the original church and later Christian institutions. This is a separate topic from the documentary and is considered a myth by some scholars

. Additionally, "The Lost Centuries" is the title of a 1971 British television series about the period in British history between the Roman departure and the Renaissance, unrelated to the documentary or the religious claim

. In summary, the phrase "The Lost Century and How to Reclaim It" most prominently refers to the 2023 documentary by Dr. Steven Greer about UFO secrecy and lost technological and spiritual progress, which advocates for reclaiming this lost potential for humanity's future.