London was a mighty port because of the cargoes that passed through its docks and wharves, but huge numbers of people also moved through the port.
Millions were emigrants or immigrants seeking a better life here or elsewhere. For them, long-distance travel by sea was the only option before air travel became common.
To cater for the movement of thousands of people, shipping companies built the great liners that became the best known ships afloat.
As the numbers of travellers grew, special facilities for them were created in the port.
However, by the late 1960s, airlines had captured the long-distance travel market. This brought an end to the era of the great liners. More people now travel in and out of London than ever before, but very few do so by sea.
The hundreds of aircraft crossing the skies over London each day have replaced the huge liners that once sailed into the port. However, the market for pleasure cruises has grown considerably, and luxury cruise ships still occasionally visit London.