
Marker
Grey paper, flat marker strokes in bands, white gouache on top.
The architectural sketch is a language of presentation: perspective is built from eye level and material is shown by a drawing convention rather than by a photograph. The four styles here follow four tools — marker on grey paper, fineliner with watercolour, monochrome ink wash, and line engraving on a toned sheet.

Grey paper, flat marker strokes in bands, white gouache on top.

Fineliner and watercolour past the outline, edges unfinished.

Monochrome sepia in layered washes; the bare paper is the light.

Line engraving on toned paper, traces of the press visible.
A wash is heavily diluted ink laid in layers: each layer darkens the tone a little while the light stays as bare paper. It is the academic way to show volume and plan without colour.
Marker lays flat bands of even tone and does not blend on the paper, which gives a graphic look and visible strokes. Watercolour runs past the outline and leaves edges unfinished.
Yes: describe the building, interior or detail in words — the rendering style stays the one you picked on the card, and the subject is yours.