To date, scholarship on urban memory has focused primarily on the city’s surface with insufficient research conducted into the mnemonic qualities of the places and landscapes that lie below the world’s metropolises. This chapter therefore argues for the greater investigation of urban memory in subterranean spaces in order to think through its vertical alignments and volumetric qualities. After recounting the groundwork studies on urban memory and noting their surficial bias, it turns to the research agendas of vertical urbanism and volumetric geography, and the setting of underground railways in order to inspire a more three-dimensional approach to urban memory. It then conceptualises this approach, with regard to underground railways, using the notions of ‘buried memory’ and ‘networked remembrance.’ Finally, by briefly presenting two case studies relating to the struggle to memorialise a victim of far-right violence in Berlin’s Samariterstrasse U-Bahn station and the heritagisation of London’s disused Aldwych Underground station, it illustrates the value of investigating questions of urban memory in the more taken for granted subterranean margins of the city.