It’s official title is actually ‘Llanberis RAF Reserve Depot (Bomb Store)’ – In 1939 two open quarries were bought by the Air Ministry for use as ammunition storage. The depot consisted of two levels, with access to the lower level by either narrow gauge railway or by truck to delivering the ammunition. Bombs could be moved through the 3 levels of the site by means of lifts within the buildings. In 1942 the site suffered a massive roof collapse burying 14’000 tons of bombs – at the time close to 20% of the total amount of bombs the RAF had at its disposal. The site had only been operational for 6 months when this occurred. Bombs were never stored at the site thereafter. Despite this the building was used till 1956 mainly for the disposal of ordnance. In 1966 a team were finally sent to clear all the remaining unexploded bombs on the site, this took nearly 6 years to complete.