The Catholic Information Center (for decades better known as the Paulsit Center) at 5 Park St. (right on the Boston Common) is prime real estate. The story of how the Paulists acquired it is fascinating. They were invited by Cardinal Cushing to start ministry in the 1940s, who purchased three houses on this strip of Park St. by proxy. This was the heart of Boston, right next to Beacon Hill, and anti-Catholic prejudice was still quite high. He then gave the proprety to the Paulists. Three rhouses not being the best setting for ministry, they tore them down and built the Center (a 6 story structre), which was dedicated in 1956. The Chapel was designed very intentionally in a low-key Puritan style and dedicated to the Holy Spirit. It's sparse, but appealing. I even found the modern crucifix (and normally I'm not a huge fan of modern art) to be quite beautiful and (importantly, given its setting) to help inspire prayer.
The priests live on floors 4 & 5 ... and the fifth floor has this amazing patio overlooking the Common.
Here's a few photos. Several more can be found on my Flickr page. [Ok that's the last time I try to align the photos to the left. Am too tired and the connection too slow for me to try and change it. This looks better in IE than Firefox. I should add that the stained glass is one of four interesting pieces at the back of the Chapel. This one depicts St. Paul, and also Fr. Isaac Hecker, the founder of the CSPs, at the feet of Pius IX, getting permission to start his missionary congregation.]