There’s no better day of the year than St. Patrick’s Day to indulge in a Guinness. But before you kick back a glass of the dark brew, here are three cool facts you might not know about the beer. Guinness Storehouse Archivist Eibhlin Colgan came to Boston from Dublin earlier this month to introduce the label’s craft brews that borrow from recipes written eons ago.

The microbrewer beers — the Dublin Porter and the West Indies Porter, originally announced in 2014, and arrived in stores last month — have an awesomely nerdy historical past that traces back to the 18th and 19th centuries. 

“We’re a brand that actually has our history,” says Colgan, “and for us to be able to go back some 200 years and look at a recipe to create a new one is what’s really exciting for me.”

Here are three more archive-kept factoids, you might not already know:

Barkeeps in Ireland used to be able to make their own labels

Back in the day, bar owners were able to create their own spin on the classic Guinness label. Fonts, colors, shape and formats were left up to them — though from what we’ve seen, most stuck to a similar formula —and Guinness kept track of the labels and their associations in an enormous roster still kept in the Dublin Storehouse today. 

Guinness will share their secrets… if you’re the Queen of England

The original 1759 lease to the Guinness Brewery, written on calfskin and signed by Arthur Guinness, and the hand-written recipe book containing their beer’s ubiquitous formula are kept under temperature-controlled lock and key within the archive. However, if you’re a celebrity or a “very special VIP” you might have a good shot at taking a peek. 

“We had Matt Damon in before Christmas and we showed him [the recipe book] — when the Queen of England came three years ago, we would show her the lease, same with Tom Cruise who came two years ago.”

And the visitors are getting wiser

As American craft and home brewing continues its cult-like following, we wondered if aficionados have more intricate and educated questions than ever when asking the experts at the Storehouse.

“We’re definitely getting a lot more detailed questions about our recipes, ingredients and process than we have before,” laughs Colgan. “The good thing is we have all the documentations and the records so we can easily take part in those kinds of conversations.”