The Principia is Camp Jupiter's headquarters.
"The outside of the Principia looks like a two-story wedge of white marble with a columned portico like an old fashioned bank. Over the doorway hung a big purple banner with gold letters 'SPQR' embroidered inside a laurel wreath." ~Percy Jackson
The celing glitters of a mosaic Romulus and Remus under their adopted mother she-wolf Lupa. The walls are draped in velvet and the floor polished marble. Along the back wall stands a display of banners and wooded poles studded with bronze metals-military symbols. In the back corner, a stairwell leads down but is covered by a row of iron bars like a prison bars