As Beijing has lowered its emergency response to COVID-19 from level II to III, a number of parks and tourist sites have reopened their indoor exhibition halls to visitors, according to a report of chinanews.com.

The Palace Museum, also known as the Forbidden City, reopened its exhibition halls such as the Gallery of Clocks and the Treasure Gallery, from Tuesday. According to the website of the museum, a maximum of 12,000 visitors are allowed in every day and reservations should be made in advance.

In addition to the Palace Museum, some other famous tourist attractions, including the Beijing Zoo, the Summer Palace and Jingshan Park, have also reopened their indoor exhibition areas.

The limit for tourist numbers has been raised from 30 percent of capacity to 50 percent in these tourist sites.

Meanwhile, measures have been put in place to prevent the epidemic.

Before entering indoor areas, visitors are required to have their temperature checked and show "green" QR codes on their mobile phones – which serve as a proof of good health.

After going into the indoor areas, tourists should wear a mask and keep a distance of no less than 1 meter from each other. Tourists are also required to wear a mask in crowded and closed places.

Despite the reopening of the tourist spots, officials of the city government warned that it is too early to relax vigilance.

"There are still many unknowns surrounding the COVID-19 virus and sources of infection are hard to detect, which means we still face a grim situation in epidemic prevention and control, and the virus will coexist with humans for a quite a long period," said Chen Bei, deputy secretary-general of the city government, at a media conference on July 19.