The Breumel in the Walls is the highest and best plot of the Haardter Bürgergarten. As a monopoly location owned solely by Müller-Catoir, it has retained its originality for centuries. A high sandstone wall protects the enclosed location from cold air influences and ensures a unique microclimate. The south-east facing location heats up very quickly in the morning, but cools down most noticeably in the evening due to its proximity to the edge of the forest. The deep soil is more barren than in the lower part of the Bürgergarten and consists of pure red sandstone gravel with a high proportion of decomposed stone.