BEIJING, July 21 -- A 24-hour bookstore opened on Monday at a former garrison tower in downtown Beijing.

The shop, run by state-owned Cathay Bookshop, is located at Yanchi Tower, an ancient garrison tower built in 1420 and renovated in 2014.

Yanchi Tower, literally translated as "wild goose's wing tower," is a two-story hip-and-gable-roofed building with yellow roof tiles.

It sits on the central axis of Beijing north of Jingshan Park, two kilometers from the Forbidden City, home to China's emperors from 1420 to 1911.

The Cathay Bookshop, founded in 1952, is the biggest state-owned enterprise dealing in antique books. The round-the-clock book shop offers not only antique books, but popular novels and children's books, according to manager Yu Huagang.

Beijing opened its first 24-hour bookstore in April 2014.