Vienna's Lainzer Tiergarten is easily reached with the city's U-4 or S-45 trains.
From Hütteldorf Station it is only 10 minutes walk to the Nikolaitor.
One of the main reasons I introduced my Ethiopian running friend to the Lainzer Tiergarten is that it's a place where you can run safely without any fear of being chased by dogs, a perennial hazard for runners.
The wild pigs are very shy and they won't chase you if you stick to the signed paths and trails. We glimpsed one pig from a safe distance. And later we met this one at the Lainzer Tor Information Centre close up.