Simultaneous substitution of W VI by U VI and Bi 3+ by La 3+ in the structure of ferroelectric Bi 2 WO 6 results in stabilization of the archetypic tetragonal I4/mmm structure which is observed for the first time among [Bi 2 O 2 ][BO 4 ] Aurivillius-type oxides. Studies at the largest U content revealed a new Aurivillius-like compound Bi 1.5 La 0.5 UO 6 which exhibits a novel distorted orthorhombic version of the archetypic structure. Formation of monoclinic α-(Bi,Ln) 2 WO 6 structure is suppressed when W is partially substituted by U. Very similar tendencies are observed when proceeding to the derived structure of PbBi 3 WO 8 Cl. Besides the tetragonal PbBi 3 W 1− y U y O 8 Cl (0⩽y⩽0.9) and orthorhombic PbBi 3− x La x UO 8 Cl (0.2⩽x⩽0.4) solid solutions, we were able to prepare PbBi 3 W 1− y U y O 8 Br (0.1⩽y⩽0.8) and a line phase PbBi 3 W 0.5 U 0.5 O 8 I which is a yet rare example of bismuth-based perovskitic oxyiodides. We discuss the factors governing formation of complex layered intergrowth structures, in particular from simpler layer sequences.