For my Roman deck, I've left the suits the same as in a standard Tarot deck, substituting denarii, Roman currency, for pentacles or coins. Instead of knights I have centurions, and Emperors and their consorts take the place of Kings and Queens.
Julius Caesar and Calpurnia are the Emperor and Empress of the suit of wands; Augustus and Livia of swords, and Constantine and Fausta the suit of cups. One possibility I've considered for the suit of denarii is Titus and Marcia Furnilla, since the Coliseum was completed under his reign.
For the Major Arcana, I'm using chiefly Roman gods and goddesses. I've come up with several cards in this category, which are pretty straightforward:
Vesta: The High Priestess
Jupiter and Juno: The Emperor and Empress
Venus and Adonis: The Lovers
Fortuna: Wheel of Fortune
Diana: The Moon
Apollo: The Sun
For the back of the cards, I decided to go with a mosaic motif, since this art form was so prevalent in Roman culture. Creating a deck in this way is a lot of fun. Thinking about the images I want to use and why allows me to further my understanding and appreciation of the cards and their symbols. Incidentally, there is a Roman Tarot currently in the works, by artist Christine Cianci. She draws upon Etruscan and Roman art to create images that truly evoke that era.