The exhibition features 40 World Heritage sites from 25countries - all made of plastic Lego bricks.
Lego builders from Hong Kong helped to build the exhibits using more than 500,000 bricks. The World Heritage sites include Italy's Colosseum, an ancient Roman amphitheatre in Rome; Spain's Sagrada Familia, a huge Catholic church in Barcelona; India's Taj Mahal mausoleum; the Great Wall of China; and Japan's Shinto Itsukushima Shrine.
Another iconic Japanese landmark, Mount Fuji - granted World Heritage status only last month, along with 18 others - is also included in the Cityplaza exhibition.
In all, Unesco has approved 981 World Heritage sites.
Endorsed by both the National Federation of Unesco Associations in Japan and the Unesco Hong Kong Association, the display hopes to inspire visitors to treasure the world's precious cultural resources and live in harmony.
The exhibition has toured Japan since 2003. Hong Kong is the first stop of a world tour, and the pieces remain on show until July 31.