Well, they're no more secret than the key to happiness, which we'll reveal at 11:31 a.m., on the dot, on Monday. But these often little-noted spots are undoubtedly naturally cooler than where you are right now. They include beaches within Boston's city limits; a wildlife preserve where you have decent chance of spying porpoises; a fishing hole; several promenades; and a dog-friendly park in Mid-Cambridge.
· Our Curbed Maps archive [Curbed Boston]