I remember my first solo experience. My cousin held the bike and ran behind me in a fenced school yard. I was yelling stop STOP STOP as I plowed into the chainlink fence as I was finally riding myself. He was about two hundred feet away.
But as kids we could ride to Long Island Sound or whatever that part of the waterway was between The Bronx (home) and La Guardia Airport - vacant lots and abandoned roadways. We watch propeller driven airplanes take off and land. This was decades ago.