Memory of Mankind: A Million-Year Archive in an Austrian Salt Mine

Memory of Mankind (MOM) is a long-term knowledge-preservation project founded in 2012 by Austrian ceramicist Martin Kunze, inspired by Alan Weisman's book *The World Without Us* and its observation that fired ceramic is among the most durable human-made materials. The archive stores information on stoneware ceramic tablets, 20 by 20 cm, with text and images either printed at 300 dpi or, in a 'ceramic microfilm' format, packed at up to 5 million characters per tablet. The ceramic resists temperatures up to about 1,200 degrees C, along with water, chemicals, radiation, and magnetism, so the recorded information becomes physically part of a near-indestructible object. The tablets are stored deep in the Hallstatt salt mine in Upper Austria, the world's oldest continuously worked mine. A salt environment is ideal for archival storage: it absorbs moisture, is geologically stable, and self-seals fractures, keeping caverns dry and watertight. The same salt-mine logic explains why Iron Age artifacts emerge from Hallstatt looking remarkably fresh. The project is designed to endure roughly one million years; because geological processes will slowly lift the deposit toward the surface over hundreds of thousands of years, organizers estimate a roughly 40-year window to fill the archive. To solve the 'how will anyone find it' problem, MOM distributes small ceramic tokens (about 6.5 cm) worldwide, each marking Hallstatt's location and the archive entrance like a treasure map, with instructions for gatherings every 50 years to check on preservation. MOM is one of the clearest real-world implementations of the salt-mine ceramic-tablet strategy discussed in Caching a Civilization Restart Kit: What Actually Survives 3,700 Years, and in 2024 it received a 5D-storage copy of the human genome (see 5D Optical Data Storage: Etching Data into Quartz for Billions of Years).