- Tonu city is a fictional city created by LEGO as part of the BIONICLE franchise. It is located on the island of Mata Nui and serves as the home for the biomechanical beings known as the Matoran. Tonu city is known for its unique architectural design, with buildings made from organic and mechanical elements. The city is divided into various districts, each representing different elements and cultures within the Bionicle world. In the center of the city is the Great Temple, which serves as the political and religious center for the Matoran. Overall, Tonu city is a vibrant and diverse city that plays a significant role in the Bionicle storyline.