A man walks in Volksgarten in Vienna, Austria, Oct. 12, 2020. (Xinhua/Guo Chen)

People walk in University of Vienna Botanical Garden in Vienna, Austria, Oct. 12, 2020. (Xinhua/Guo Chen)

A pigeon stands among the fallen leaves in Volksgarten in Vienna, Austria, Oct. 12, 2020. (Xinhua/Guo Chen)

A staff member cleans fallen leaves in Belvedere Palace Garden in Vienna, Austria, Oct. 12, 2020. (Xinhua/Guo Chen)