It's a complex of palaces open to the public and tourism. Has that name because, in the past, to enter there the people needed to have express authorization from the emperor since during the Ming dynasty and until the end of the Qing it was used as a home for emperors as well as to deal with political issues. It was declared a World Heritage Site in 1987.
In relief printing, the artist draws a design on a smooth block of material—usually wood or linoleum—and uses tools to carefully cut away the areas that are not to be printed, leaving behind a raised surface of lines and shapes.
