In 1984, the college of aldermen decided to bring all of Luxembourg City's various photographic collections together into one place, resulting in the creation of the Photothèque (Photographic Archive). Its purpose is to document Luxembourg City's evolution through its various phases of urban development, and to provide public access to its documents, subject to certain rules.

It is consulted by journalists, publishers, architects, collectors, teachers, students, museums, etc., and is always looking to supplement its existing collections (old photographs, postcards, etc.) through new acquisitions, which are often subject to conditions agreed upon on a case-by-case basis.

The photographic archive's collections now contain approximately three million photos taken between 1855 and the present day. They have been built over the years through donations, bequests, acquisitions of collections and reports commissioned by the City. The Photothèque is continuously expanding its collections through new acquisitions.

In 2011, electronic archives were established. Since that time, three million photos have been scanned manually. 250,000 have been indexed into a database. Every image recorded also displays the year the picture was taken, and the indexing system provides a more detailed description of the location or context in which it was taken, as well as of the work itself. It also provides information about the photographer and their origins and, lastly, details about the negative and applicable copyright. This indexing facilitates searches within the archives, making the Photothèque's contents more easily accessible to the public, who can purchase copies of the photos in paper or digital format.

Particular care is taken over the optimal conservation of our documents. For example, negatives are archived separately from paper documents in a climate-controlled room, ensuring the long-term preservation of this fragile material.

Albums may be consulted on site for free, for various kinds of research. However, visitors must pay if they want copies of the images.