Adam Letch's photo of a chapel built on Bosjes farm in Ceres, Cape Town.[Photo provided to China Daily]

The finalists from four image categories - exterior, interior, "sense of place" and buildings in use - were selected from thousands of entries after two rounds of judging. The overall winner was voted for by visitors to the festival.

Another of Zhang's photos that showed a gymnasium at Tianjin University topped the category of buildings in use.

The pool and the gym Zhang photographed were designed by Atelier Li Xinggang. Li was the Chinese team leader of the design team behind the National Stadium in Beijing.

Zhang shot the swimming pool in November 2016, after talking with Li about the design concept. The temperature was 0 C outside and about 20 C inside. So the vapor was reflected in the sun.

"I've never seen such clear light - it was like a fairy tale," the 31-year-old photographer says, adding that he waited until all the students had left the pool.

Zhang used to be an architect. He turned to photography six years ago when he found his passion to capture the look of buildings surpassed his desire to design them.

"You can't be a good architectural photographer unless you are a fan of buildings," Zhang says.