The above is the fabled porte du temps (door of time), located in the Somonite desert. All three of these images / locations appear in L’archiviste, a companion book to the series. (I’m making this post because of the nice intro to book three published yesterday, here)

Le Lac Vert, Arrivee de l’Expédition Loms-Nered (the Green Lake, setting for the arrival of the Loms-Nered expedition)

The Obscure Cities (Les Cités Obscures) is a BD series created by Belgian artist François Schuiten and French writer Benoît Peeters. First serialized in magazine format in 1982, the series has been published in album format by Casterman since 1983. New installments of the series were published throughout the 1980s, 1990s, and 2000s in varying formats, including full-color, partial color, greyscale, and B&W, as well as photo comic, picture book, and multimedia formats. The series is distinguished by Schuiten’s realistic rendering of diverse contemporary, historical, and imaginary architectural styles. --WP

Mont Michelson - La Distraction de l’Astronome

In this fictional world, humans live in independent city-states, each of which has developed a distinct civilization, each characterized by a distinctive architectural style. The series has no unifying narrative, instead telling a series of unrelated stories, using its fictional setting as the basis for magic realism and social commentary.

Schuiten’s graphic representations and architectural styles is, among other historical themes, heavily influenced by Belgian Art Nouveau architect Victor Horta, who worked in Brussels at the turn of the 20th century. An important motif is the process of what he calls Bruxellisation, the destruction of this historic Brussels in favor of anonymous, low-quality modernist office and business buildings. --WP

A nice overview and wiki-resource for the series is HERE, in English & French.