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 Much private land was now open to the public, particularly around the inner harbour and the north side of Roath basin. Work is progressing to complete a 13 kilometre walkway around the bay. In addition, the development has enabled land in the city centre to be redeveloped for higher-value uses. The development of "something like 1,250 apartments a year" however might cause future problems. As at 2008 up to one third were not occupied. Critics such as Lorraine Barrett (AM Labour, Cardiff South and Penarth) say, the flat complexes will not help to build up a community and too little