The Visitor Center itself is also stunning. It's this huge brick building right on the banks of the Reservoir.Inside there are many displays. I liked this one that showed how the town of Enfield was literally removed so that they could flood the town as part of the Reservoir. The first pictre shows the town. (Pay attention to the landscape of the hills as you'll see the same hills in all three pictures.)
Here's Enfield 12 years later - gone!
And here it is today. Amazing!
One scary thing about the Quabbin is that it is under threat of the horribly invasive Zebra Mussles. So far, they are not in the Quabbin, but they are in some nearby bodies of water and the risk of contamination is quite high. They've implemented some new rules to protect Boston's drinking water supply and I hope they work.