Heraldic shield with cool snake vector illustration and laurel wealth on dotted red background. Serpents are one of the oldest mythological symbols and represent poison and medicine, guardianship, revenge, fertility, transformation, healing, immortality and rebirth.
A remix of http://www.openclipart.org/detail/631 originally derived from the US government EPA "Sunwise" program. I converted it from PDF format. the source link is here - http://www.epa.gov/sunwise/doc/poster.pdf
There is more detail on the doors.