Why are breasts so fascinating?

I ran across a story entitled "Court Upholds Woman's Right for Topless Protest", and I immediately thought: why are breasts so fascinating? Let me qualify that: why are women's breasts so fascinating? For my entire life, I've wondered why it is acceptable for men to wander around town topless but not for women? Why is it ok for C to take his shirt off at the beach and not for me? I don't know that I agree that going topless is a viable means of protest, but if it is legal to burn the flag as a form of protest, why can't women take their tops off?