For those in Vienna on Sept 27 and or Sept. 28, I highly recommend the Wiener Weinwandertag, or the Vienna Wine Hiking Day.
The city of Vienna annually puts together a set of four hikes/walks through vineyard areas of the city. The event is free and features well marked trails through gorgeous scenery, often from high up on the Vienna hills. (Note - Vienna produces a significant volume of wine within its city limits, making it much more of a Wine Town than a Beer Town).
As you walk on the trails, you will encounter stalls selling food, wine and other treats from local wineries. Most special this time of year is a glass of Sturm, a very young wine which is fizzy and very delicious, but packing a wallop. I highly recommend Sturm.
Of the four trails, the classic is Route 1, which will be the most crowded. Route 2 is on the other side of the river and includes the charming Stammersdorf. My personal favorite, Route 4, takes you to great lookouts to the south and passes the quite iconic Wotruba Church.
If you are in Vienna, please check it out!