The timber for building Forbidden City is a special kind of wood called phoebe. This kind of wood have higher density than normal wood and it is hard to find and emperor only use high quietly of timber this makes the building even harder.
After the wood has been cut from the southwest provinces, along the Yangtze River and Zhejiang and Jiangxi’s deep forests, workers transported timbers out by the use of the rivers. (From south province such as Sichuang, transport need spend 3 to 5 years.) And in the city, they used many gold brick that forged in southwest provinces; large brick come from north-east provinces; the printing color come from East Providence; other stone such as White marble are come from provinces near by Beijing.