 Because of its shape, it was named "Rainbow Pier".In the late 1940s, the City of Long Beach began filling in the water area enclosed by the Rainbow Pier breakwater, creating Rainbow Lagoon and Wilmore Park, ["sic"] additional public trust lands upon which a larger, more modern auditorium was constructed.Filling of the shoreline area continued in the late 1950s and early 1960s with the Tidelands Filling Project.