Lakeville Hospital was a state-operated sanatorium in Lakeville MA. It opened its doors in 1910 to treat those who had tuberculosis. In the 50s, following a decline in the number of tuberculosis cases, the sanatorium began treating patients with other conditions. The hospital was closed in 1993, and its surrounding area is secured to prevent unauthorized entry.
WARNING: This place is heavily patrolled! The closest we got was the sidewalk and a (very kind) police officer almost immediately drove up to us to ask us questions. I advise that if you are planning to go, make sure you are prepared to be stopped. Personally, it's not worth the trip unless you actually were able to get inside which may or may not be impossible.

The Lyman School for Boys in Westborough MA was founded in 1846 and closed 1971. It was the first training school in the United States and held males 9 to 18 years of age.  Every year approximately 300 boys "graduated" from the college campus looking school.  Today, it remains a nationally registered historic place. However, there are new buildings on the grounds and we had to get permission from a security guard to roam around. We didn't go inside any of the buildings but the walk through was enough in itself.