There are several levels of complexity, which only differ in the size of the mosaic grid available (and thus how detailed a picture you can make).
Raeli Tiles are needed to make the mosaic tiles used in the picture. If you are in need of Raeli Tiles, but do not have access to an oven (or to an oven that produces the colors you want), browse to the Tile Trading Page.
Built: inside, using 37x28 cells
Skill/Tech required: must be signed up for the Test Of The Raeli Mosaic
To view current Mosaics, check out the Museums