MIT, but it's not really a fair question because the Boston startup scene isn't shaped like a bullseye. It's really two lines, following major traffic arteries. The city corridor is along the Red Line, from Davis to South Station. The suburb corridor is Route 128, from Rt. 3 in Burlington to Needham.
Both of them don't really drop off with distance - Davis (near the end of the red line) is as much of a startup center than Central, and Burlington (the northern end of the 128 corridor) is more of one than Weston (though this isn't really fair: Weston is a bedroom community for all the venture capitalists that fund them). They do, however, drop off dramatically if you move laterally: Billerica and Carlisle are rural bedroom communities, dramatically different from the high-tech industries in neighboring Bedford and Burlington.
Both of them don't really drop off with distance - Davis (near the end of the red line) is as much of a startup center than Central, and Burlington (the northern end of the 128 corridor) is more of one than Weston (though this isn't really fair: Weston is a bedroom community for all the venture capitalists that fund them). They do, however, drop off dramatically if you move laterally: Billerica and Carlisle are rural bedroom communities, dramatically different from the high-tech industries in neighboring Bedford and Burlington.