In January 2013 the Industrial Gas Museum gave the Greek public and the visitors of Athens a chance to take a new glance at the Greek capital’s past and wander into the buildings of an energy unit that operated more than a century at the city’s heart. Though most of the plant’s equipment has been maintained (TICCIH Bulletin n.62), only a few items out of the company’s archive have survived up today. Since 1984 that the Athens Municipal Gasworks Company (as it was renamed, after the French company dropped out in 1937) stopped operating, the premises were sealed till the mid-1990s. During that obscure period, the factory’s archive was carried away and no one heard anything of it in the years to come. This paper presents the technical drawings collection and discusses the need of preserving business archives.