TIL The Zero Milestone is a zero mile marker monument in Washington, D.C. intended as the initial milestone from which all road distances in the United States should be measured when it was built.

https://en.wikipedia.org/wiki/Zero_Milestone

https://www.reddit.com/r/todayilearned/comments/15s2sej/til_the_zero_milestone_is_a_zero_mile_marker/