We think of particle physics as making progress when we probe smaller and smaller size scales, but sometimes new signatures can show up far away from highly energetic particle collisions. I explain why Long Lived Particles (LLPs) could be the harbingers of new physics beyond the Standard Model, and why they are motivated by some of the most fundamental mysteries in particle physics today, like the Matter-Antimatter Asymmetry of the Universe, Dark Matter, and the Hierarchy Problem. LLP signatures can be spectacular but are easily missed in standard searches, which could be the reason that we have not yet seen new physics at CERN's Large Hadron Collider. Exploring this Lifetime Frontier requires new capabilities. I will introduce the MATHUSLA proposal that aims to build a large but relatively simple detector on the surface at CERN to catch these elusive LLPs, and also discuss other detector proposals that MATHUSLA has inspired. Together, these new experiments may hold the key to discovering the missing puzzle pieces of new physics that could be hiding at the Lifetime Frontier.