City map relief in the Karlsruhe Pyramid, Weinbrenner's city map of Karlsruhe engraved in limestone

The city map relief in the Karlsruhe Pyramid is a 100 by 74 cm limestone slab, 6.7 cm thick, engraved with Karlsruhe at a scale of 1:4200. A 45 mm grapevine frieze frames the edge, with oval compass vignettes at the middle of each side and a 75 mm inscription band above the lower edge. Hatched areas were originally filled with yellow, blue, red and green pigments marking construction phases.

Architect Friedrich Weinbrenner designed the relief in 1823, created by the workshop led by Johann Jacob Meyerhuber. It was placed inside the Karlsruhe Pyramid, a tomb for Karl Wilhelm of Baden-Durlach, where it documents the city's growth across different periods of rule.

The relief carries a seven-line inscription in a modern variant of Roman capitalis, centred below the map, that names the margraves and grand dukes under whom Karlsruhe expanded. It is set entirely in capitals but separates words with spaces, unlike ancient inscriptions, and writes "J" as "I", as in "IETZT". Only "GEGRÜNDET" keeps an umlaut; elsewhere digraphs such as "VERSCHOENERT" are used.

The relief is kept in the middle of the three chambers of the Karlsruhe Pyramid, on a sandstone base. It was removed on 17 September 1998 after plaster fell from the ceiling and damaged it, and returned in September 2018 after restoration and the subway construction. Look for the crack in the left third running north to south, near today's Europaplatz.

The map displays the city in different phases of growth, with each color representing a separate ruler and era. This color-coded layering of time allows visitors to visually trace how Karlsruhe expanded piece by piece.