Photo taken on Aug. 16, 2020 shows the view over Vienna from the Kahlenberg Panoramic Viewing Terrace, in Vienna, Austria. The Kahlenberg Panoramic Viewing Terrace is one of the famous viewpoints in Vienna, which overlooks the city and attracts lots of tourists. (Xinhua/Guo Chen)

Photo taken on Aug. 16, 2020 shows the view over Vienna from the Kahlenberg Panoramic Viewing Terrace, in Vienna, Austria. The Kahlenberg Panoramic Viewing Terrace is one of the famous viewpoints in Vienna, which overlooks the city and attracts lots of tourists. (Xinhua/Guo Chen)

Photo taken on Aug. 16, 2020 shows the view over Vienna from the Kahlenberg Panoramic Viewing Terrace, in Vienna, Austria. The Kahlenberg Panoramic Viewing Terrace is one of the famous viewpoints in Vienna, which overlooks the city and attracts lots of tourists. (Xinhua/Guo Chen)

Photo taken on Aug. 16, 2020 shows the view over Vienna from the Kahlenberg Panoramic Viewing Terrace, in Vienna, Austria. The Kahlenberg Panoramic Viewing Terrace is one of the famous viewpoints in Vienna, which overlooks the city and attracts lots of tourists. (Xinhua/Guo Chen)

Photo taken on Aug. 16, 2020 shows the view over Vienna from the Kahlenberg Panoramic Viewing Terrace, in Vienna, Austria. The Kahlenberg Panoramic Viewing Terrace is one of the famous viewpoints in Vienna, which overlooks the city and attracts lots of tourists. (Xinhua/Guo Chen)

Photo taken on Aug. 16, 2020 shows the view over Vienna from the Kahlenberg Panoramic Viewing Terrace, in Vienna, Austria. The Kahlenberg Panoramic Viewing Terrace is one of the famous viewpoints in Vienna, which overlooks the city and attracts lots of tourists. (Xinhua/Guo Chen)