Monumentum were formed in Milan in mid 1987 by guitarist Roberto Mammarella and bassist Anthony Duman, who recruited vocalist Mark Westfall and drummer Mox Cristadoro.Between December 1988 and April 1989, the band recorded and mixed the five song demo Musaeum Hermeticum, which was released as a limited edition cassette of 180 copies.Two tracks, "Nostalgia of the Infinite" and a cover of The Dead Relatives' "Nephtali", were selected by Obscure Plasma Records for a split single with the Greek black metal band Rotting Christ in 1991.
Following a brief split, Monumentum were picked up by the predominantly black metal Norwegian label Deathlike Silence Productions.However, before the proposed album could be released, DSP owner Øystein Aarseth was murdered. The album, In Absentia Christi, recorded and mixed between August 1994 and May 1995, finally saw the light of day through the British label Misanthropy Records. The recording line-up featured two vocalists, in the form of Andrea Zanetti and Francesca Nicoli (of Ataraxia, alongside Mammarella ("strings, keys and vibas"), Cristadoro (drums) and Paolo Mauri ("samples, artistic production and wisdom"). Activity from the band became sparse until reuniting to record "The Colour of Compassion" for Misanthropy's anti-censorship compilation Presumed Guilty (1998). Further compilation appearances included the Death SS tribute album Beyond the Realm of Death SS, to which Monumentum contributed a cover of "Black & Violet" with Cornelius Brastad of Solefald on vocals
Monumentum reunited in 2001 to record Ad Nauseam for Tatra Productions. The line-up had changed again; Ad Nauseam featured new vocalist Andrea Stefanelli among other new musicians.