Probably the best know dark nebula - at least at northern hemisphere!

Object: Barnard 33 - Horsehead nebula
Type: A huge complex of emission, reflection and dark nebulae
Constellation: Orion (Ori)
Location: RA: 05h 41m 00s DEC: -10 46 17
Brightness: n/a
Size: Ca 1 degree

Interesting and "photogenic" area of the sky, often photographed. The red "background" for the Horsehead is emission nebula IC434. The head itself is a dark nebula B33. A flame nebula is visible close to the brightest star - Alnitak.

The Horsehead is notoriously difficult visually, the nebula behind has very low brightness so contrast is always very low. A quality narrowband filter (OIII, Hb) and large telescope is almost mandatory. No doubt why it was discovered only on photographic emulsion!