Portal apparatus (40) is provided for interconnection between adjacent first and second structures (32, 34) in order to maintain operative communication between the structures (32, 34) under seismic conditions. The apparatus (40) includes a portal assembly (36) together with coupling assemblies (38, 40) permitting translation and rotational movement of the portal assembly (36) about three orthogonal axes (X, Y and Z) in space. The first coupling assembly (38) serves to secure assembly (36) to structure (32) and permits rotation about and translation along the X axis, as well as rotation about the Y and Z axes. The second coupling assembly (40) slidably connects the remote end of assembly (36) to structure (34) and accommodates Y and Z axes translation.