If you're interested in Roman history you will undoubtedly be directed to Dewa Roman Experience. I found it to be quite disappointing and more concerned with gimmicky displays of what it must have smelled like than any useful information. At 5 british pounds it's also kind of pricey.
Unique Suggestions: The most interesting part of the tour is the 'excavation' in the basement that shows the different layers of development: Roman, Saxon, Medaeval, modern. Here at least you get a sense for what archeologists experience.
Fun Alternatives: Save your money and head over the the Grosvenor museum. It's free and has a much better collection of artefacts with much better presentation.
Watch out you don't get caught by a Roman Soldier ;-)
Unique Suggestions: Seriouly though a "roman soldier" can be obtained for guided tours of Chester - just ask at the tourist information centre by the town hall.
Also this Roman soldier is an advert for the "Deva Experience" where you can step aboard a roman galley ship and reconstructed streets of old Chester - just like the Jorvic viking centre in York.Location Pierpoint Lane just off Bridge St.