LEGO maintains a secret, high-security vault in Denmark containing almost every set ever made.

The LEGO Memory Lane vault is situated in the basement of the LEGO Idea House in Billund, Denmark, the town where the company was founded in 1932. This high-security facility serves as a definitive archive, housing approximately 8,000 to 10,000 unique sets dating back to the company's origins. While the collection is nearly complete, some early wooden toys and specific sets from the 1940s and 1950s are missing due to historical gaps before formal archiving began.The environment is strictly climate-controlled to prevent the degradation of Acrylonitrile Butadiene Styrene (ABS) plastic, which is the primary material used in LEGO bricks since 1963. UV light is completely excluded to prevent the iconic colors from fading or yellowing over time. Temperature and humidity are kept at constant levels to ensure the cardboard packaging and instruction manuals do not deteriorate. This preservation is vital because the chemicals in older plastics can become brittle if exposed to fluctuating environmental conditions.Each set is stored in its original retail packaging, and the collection grows annually as new products are released. The archive is not open to the general public, though it is occasionally featured in documentaries or opened for special guests and long-term employees. Designers frequently visit the vault to study the 'DNA' of the brand and understand how building techniques have evolved over the decades. This physical record ensures that the legacy of Ole Kirk Christiansen's creation remains intact for future generations of builders.