For example, if you look at the building in this photo, you will quickly notice that it's a two-stories building... But that not true!
The lower roof doesn't correspond to a floor, it's in fact purely decorative - an architectural technique called mokoshi 「裳階」, which can be translated as "skirt" or "cuff story".
Frequently used in Zen temples, you can see mokoshi used for gates, pagodas or halls like the one in my photo: the Daibutsuden (Great Buddha Hall) of the Tōdai-ji Temple from Nara.
EXIF info:
Nikon D90
Lens: VR 18-55mm F/3.5-5.6G
Focal Length: 20mm
Aperture: F/5.6
Shutter Speed: 1/640s
ISO Sensitivity: ISO 200