Around 500 tour participants were able to secure online reservations on Sunday, with the free tickets snapped up in just 10 minutes.

Others included invited guests such as model workers and soldiers in appreciation for their societal contributions.

Another night tour is to take place on Wednesday night. But Shan said further evaluation is necessary to determine whether regular night visits to the compound will be offered in the future.

Nevertheless, he said some important days in the lunar calendar, like the Mid-Autumn Festival, would possibly become new occasions for nocturnal tours, and more regions other than city walls might be opened after the sun sets.