Cardiff in making iron and later steel, brought to the sea by packhorse from Merthyr Tydfil. This was first achieved by the construction of a long canal from Merthyr (510 feet above sea-level) to the Taff Estuary at Cardiff. Eventually the Taff Vale Railway replaced the canal barges and massive marshalling yards sprang up as new docks were developed in Cardiff – all prompted by the soaring worldwide demand for coal from the South Wales valleys. At its peak, Cardiff's port area, known as Tiger Bay, became the busiest port in the world and – for some time – the world's
Cardiff Bay Visitor Centre (The Tube) was built to house an exhibition about the new Cardiff Bay development. In 1993 the building needed to be moved from its location east of the Pierhead Building. Rather than permanently dismantle it, the structure was put on the back of a low-loader truck and moved to another part of the Bay. It continued to house interactive exhibitions and a scale model of Cardiff. Because of its distinctive shape, the visitor centre became known locally as 'The Tube'. In 2009 it was listed ninth in the Top Ten free attractions in Wales. Cardiff Bay Visitor Centre was listed by a