Great place to spend a couple of hours and discover more about the art of herbal tea making. Sign up for a free tour as soon as you arrive (you're given a single tea bag sachet as your ticket – e.g. the "Peppermint" or "Black Cherry" group). Then before your slot (as well as afterwards!) make the most of tasting as many varieties as you want from their comprehensive "menu". Some are ready made in bulk, but they'll happily make you a cup of whatever you fancy!
The tour is interesting - a short film about the history of the company and factory, followed by a trip around the factory floor, with a great guide explaining every stage of the tea bag production. The mint room is not to be missed!
At the end of the tour is an extensive and really very good gift shop, where you can, of course, buy all boxes of all the varieties of tea that Celestial produce among other things. They're reasonably priced and, as I said, you can taste any you're interested in before making the decision to buy (which I think is great - it was hard to choose coz there were so many good ones!).