The Boston Marathon and Mayor Michelle Wu insist that international runners and other foreign visitors remain welcome in the city.

Here is an overview of the toughest miles of the Boston Marathon course, according to several past and present runners.

If you're in any of those categories, here's how you can watch the Marathon on Monday, April 21, from home or elsewhere: Live coverage of the Boston Marathon will exclusively air on WCVB-TV beginning at 4 a.m.