My diagonally-oriented distant cousins the roofs are very hush-hush about their access points because they don’t want to harm anyone, and are aware they’re both dangerous and tempting destinations to humans who like views & solitude. If you like heights and views, my 5th floor windows are quite nice. Or how about a hike up a local hill instead? I recommend Peters Hill in Arnold Arboretum (not far & an easy walk) or the Blue Hills for something a little more challenging (also further & not on public transit).