There is just a marker on the ground and no other info. If you see a lot of people standing around in a circle, the marker is in the middle of them. If you're not on a guided tour, you'll definitely want to do some research first to understand why the spot is important.

It occurred what is now Downtown Boston. located in front of the Old State House balcony. You will find a marker that indicates the site.

In front of the Old State House is a circular ground monument to recognize one of the most important events leading to the American Independence. No, neither war nor independence started here. However, it was here that people first died for an independent country when 5 colonists were killed and 6 were injured when 7 British soldiers and their officer fired shots on a crowd. While it was portrayed as British soldiers firing on unarmed civilians, it was a handful of soldiers facing hundreds of citizens throwing snowballs and wielding clubs, a fact that would enable future President John Adams to get acquittals for the officer and most of the soldiers. Still the propaganda of the shooting was far more important for the garnering colonial support throughout the colonies. It all happened here right in front of the Old State House. For all of these reasons, this is an important site for all to visit on the Freedom Trail.

It is literally just a plaque in the middle of the pavement. I think there's a museum around the corner but we couldn't work out how to get in...

The site is in the middle of an area surrounded by office buildings. It's worth a quick look because of it's significance in our Nationa's History. The cemetery down the street with the burial cites were more impressive in my opinion.