Example: Some routes between Harvard Yard and Long Wharf take you through residential and nightlife areas where a lot of people life, past biotechs, MIT, a few FAANG outposts, over a bridge with great views, across the Esplanade park, past at least a major hospital, financial district, through North End (Italian restaurants), tourist area, and to harbor walk, to sit on Long Wharf and watch the boats and airplanes.
https://www.google.com/maps/dir/Harvard+Yard,+Massachusetts+...
(Separate from walking, a lot of people bicycle here, and you'll see heavy bikes on some streets during commuter hours, but don't beware that bicyclist safety is so-so here. If you decide to bike instead of walk, watch out for car doors opening into your path, trucks making turns, negligent car drivers, other bikers ignoring road rules, mild resentment of bicyclists, etc. Personally, I just walk, and know that there's a good chance that a driver even going through the busiest Central Square intersection is looking at their phone. :)
Put it this way: Don't eat a 250 cal chocolate bar or take a 60 minute walk? Same impact.
Incidentally I have walked 103 miles in the last 24 days...
Maybe a crappy way if you are obese.
But AFAIK over years walking will strongly help maintain a good weight and keep you healthy. It certainly does help reduce weight and improve fitness compared to just potatoing. You can do more, but as a minimum starting point it is pretty bloody good.
One observation: people are generally not obese in central London and part of the reason is the few km walking per day to get to and from work via the tube.
Deuterated water studies back this up. Humans burn roughly the same amount of calories active or passive. The body only shunts the available calories around.
Now, exercise has lots of documented benefits. Weight loss just isn't one of them.