The Rosenheim Herbstfest (Autumn Festival) is one of the largest beer festivals in Bavaria after Munich's Oktoberfest, held annually for two weeks in late August and September at the Mangfallpark festival grounds. Several large beer tents from Bavarian breweries fill the site, along with fairground rides and food stalls.
The Herbstfest has a more local character than Oktoberfest — the crowds are predominantly Bavarian rather than international, and the atmosphere is relaxed and genuinely festive rather than tourist-facing. If you are in the region during the festival period, it is worth an evening. Outside festival time, the Mangfallpark is a pleasant riverside park for a walk along the Inn.