Every winter, a magical city made of ice glows brightly in north-eastern China's Heilongjiang province.

Ice castles, towers and fantastical structures illuminated with coloured lights form the centrepiece of the Harbin International Ice and Snow Sculpture Festival.

The blocks of ice used to create the vast structures are cut from the nearby Songhua River. De-ionised water is used for some structures, making them transparent.

The event, which also features the world's largest snow sculptures, has become hugely popular, drawing around a million visitors every year.

Harbin is one of coldest cities in China and is commonly referred to as "the ice city." The average temperature in winter is -16.8°C (1.8°F) and lows of -35°C (-31°F) are not uncommon.

The 31st International Ice and Snow Sculpture Festival runs in the city of Harbin from January 5 to February 25, 2015.