>>449675Oslo, Norway.
There are huge woods on both the north and east side of the city. You can take the subway to one of the suburbs, then theres maybe a 10-15 minute hike on road 'til you get to the woods. And from there you can more or less hike for days.
There is a nature reserve (with wolves!) somewhere east of here, I've never hiked that far but I plan on going there this summer.
Only problem is that Norwegians generally love hiking and going for walks, so you have to travel pretty deep into the woods to avoid people. I actualy haven't had a single trip yet where I didn't see someone.