A cigarette comprising: a lighting end (14; 714; 914) and a mouth end (18; 718; 918); a mouth end piece segment disposed at the mouth end (18; 718); and an aerosol-generation system disposed between the lighting end (14; 714; 914) and the mouth end piece segment, the aerosol-generation system including a heat generation segment disposed at the lighting end (14; 714; 914) having a length including a heat source configured to be activated by ignition of the lighting end (14; 714; 914) and an insulation layer of flame-retardant material disposed around the heat source; an aerosol-generating segment incorporating aerosol-forming material, said aerosol-generating segment having a length and being disposed between, but physically separate from, each of the heat generation segment and the mouth end, wherein the aerosol-generating segment includes a monolithic substrate (55; 600; 610; 763; 963), characterized in that the monolithic substrate (55; 600; 610; 763; 963) comprises at least one slot (602; 612) on an exterior surface thereof, that the monolithic substrate (610; 763; 963) comprises a center-hole (614; 795; 995) disposed longitudinally through a length thereof, and/or that the monolithic substrate comprises a plurality of channels longitudinally disposed therethrough, and in that the monolithic substrate (55; 600; 610; 763; 963) includes an open interior section, wherein said open interior section provides improved transport and/or aerosolization of vaporizable materials being released from the monolithic substrate (55; 600; 610; 763; 963) by heat during use of the cigarette. a lighting end (14; 714; 914) and a mouth end (18; 718; 918); a mouth end piece segment disposed at the mouth end (18; 718); and an aerosol-generation system disposed between the lighting end (14; 714; 914) and the mouth end piece segment, the aerosol-generation system including a heat generation segment disposed at the lighting end (14; 714; 914) having a length including a heat source configured to be activated by ignition of the lighting end (14; 714; 914) and an insulation layer of flame-retardant material disposed around the heat source; an aerosol-generating segment incorporating aerosol-forming material, said aerosol-generating segment having a length and being disposed between, but physically separate from, each of the heat generation segment and the mouth end, wherein the aerosol-generating segment includes a monolithic substrate (55; 600; 610; 763; 963), characterized in that the monolithic substrate (55; 600; 610; 763; 963) comprises at least one slot (602; 612) on an exterior surface thereof, that the monolithic substrate (610; 763; 963) comprises a center-hole (614; 795; 995) disposed longitudinally through a length thereof, and/or that the monolithic substrate comprises a plurality of channels longitudinally disposed therethrough, and in that the monolithic substrate (55; 600; 610; 763; 963) includes an open interior section, wherein said open interior section provides improved transport and/or aerosolization of vaporizable materials being released from the monolithic substrate (55; 600; 610; 763; 963) by heat during use of the cigarette. a heat generation segment disposed at the lighting end (14; 714; 914) having a length including a heat source configured to be activated by ignition of the lighting end (14; 714; 914) and an insulation layer of flame-retardant material disposed around the heat source; an aerosol-generating segment incorporating aerosol-forming material, said aerosol-generating segment having a length and being disposed between, but physically separate from, each of the heat generation segment and the mouth end, wherein the aerosol-generating segment includes a monolithic substrate (55; 600; 610; 763; 963), characterized in that the monolithic substrate (55; 600; 610; 763; 963) comprises at least one slot (602; 612) on an exterior surface thereof, that the monolithic substrate (610; 763; 963) comprises a center-hole (614; 795; 995) disposed longitudinally through a length thereof, and/or that the monolithic substrate comprises a plurality of channels longitudinally disposed therethrough, and in that the monolithic substrate (55; 600; 610; 763; 963) includes an open interior section, wherein said open interior section provides improved transport and/or aerosolization of vaporizable materials being released from the monolithic substrate (55; 600; 610; 763; 963) by heat during use of the cigarette.