A staff member serves beer during the first day of the Oktoberfest 2019 in Munich, Germany, Sept. 21, 2019. The 186th Oktoberfest, one of the world's largest folk festivals, officially opened here on Saturday. It is expected that around 6 million visitors from all over the world will enjoy festival beer and culinary delicacies here from Sept. 21 to Oct. 6. (Xinhua/Lu Yang)