the present invention provides an aircraft structure comprising a first sub - structure , having a first box cross - section , a second sub - structure , having a second box cross - section , and a joint joining a first end region of the first sub - structure to second end region of the second sub - structure , wherein the joint comprises an overlap region where the end regions of the first and the second sub - structures overlap such that the first sub - structure is inside the second sub - structure . the present invention also provides an aircraft comprising such an aircraft structure and a method of manufacturing an aircraft structure .