This is Navajo Arch in Arches Nationap Park, Utah.  The right time of day, and the sun lights up the interior of the "cave" formed by the arch and it appears to glow from within.

Glowing from Within
This is Navajo Arch in Arches Nationap Park, Utah. The right time of day, and the sun lights up the interior of the "cave" formed by the arch and it appears to glow from within.