The present invention provides an assembly apparatus for supporting a fuselage section of an aircraft or spacecraft in an adjustable assembly position, with at least one stiffening bow for detachably stiffening the fuselage section and a rotational support, which rotatably supports the at least one stiffening bow. Also provided is a method for the assembly of a fuselage section of an aircraft or spacecraft in which an assembly position of the fuselage section is prescribed. In further steps, the fuselage section is reinforced with a stiffening bow and the stiffening bow is rotatably supported. The stiffening bow is then turned in such a way that the fuselage section rotates into the assembly position.