chassis number

I've exported my Prius bought in the US to Spain. To get it registered here, I need for a technician here to make a rubbing (yes, like from a gravestone) of the chassis number, and I need to know where it is first. Does anyone know where the chassis number is? It's not just the VIN that's on the dash, it's engraved into the unibody, probably somewhere underneath the vehicle. It's the 2005 model. Cheers; Kirk.