An aircraft fuselage structure which is constructed from a plurality of shells which are joined together is disclosed. Each shell forms part of the aircraft fuselage and comprises a support structure and a skin which is arranged on the latter and outwardly seals the aircraft fuselage in a compression-proof manner. The aircraft fuselage structure comprises an upper and side shell and a lower shell, of which the lower shell has a radius which is essentially significantly larger than the radius of the upper and side shell. The upper and side shell and the lower shell are joined together at transition regions extending in the longitudinal direction of the aircraft. The support structure of the lower shell is designed in terms of its strength in such a manner that it is capable of absorbing the internal pressure loading of the lower shell without the use of a main crossmember.