Over-the-Rhine-based Christian Moerlein Brewing Co. will tap the first keg of its latest year-round brew, the Moerlein Barbarossa Double Dark Lager, Thursday night at Arnold’s Bar and Grill downtown. First brewed for German Emperor Frederick I – aka Barbarossa – during the 12th century, the Moerlein Barbarossa was first produced in the mid-1800s. It’s a deep reddish-brown German-style dunkel. The first tapping ceremony will happen at 5:30 p.m., but the party is from 5 p.m. to 9 p.m., according to a news release. Robert L. Pohl, the last president and chief executive officer of the original Hudepohl Brewing Co., will tap the first keg. Arnold’s is located at 210 E. Eighth St., and the event is free to the public. Free, limited-edition posters of the label will be given away during the event. For more information, go to www.christianmoerlein.com.