Jacques-Clément Métezeau (French pronunciation: [klemɑ̃ metəzo]; 1581–1652), also Clément II Métezeau, was Royal architect of Louis XIII, and French engineer who completed the seawall blocking the city of La Rochelle in the Siege of La Rochelle in 1627–1628.
The initial idea for blocking the channel leading to the harbour of La Rochelle in order to stop all supplies to the city came from the Italian engineer Pompeo Targone, but his structure was broken by the winter weather. The endeavour was finally taken up by the Royal architect Clément Métezeau (also Metzeau).
The wall was built on top of a foundation made of sunken hulks, filled with rubble. The construction involved 4,000 workmen, and the seawall was 1,400 metres long. French artillery installed on the seawall and used against English ships that tried to supply the city.
Métezeau was also involved in the building of the Palais du Luxembourg for Marie de Medicis: he was sent to Florence by the main architect Salomon de Brosse to make drawings of the Palazzo Pitti, which was to be used as a model by the regent's order.
The seawall designed by Clément Métezeau for the Siege of La Rochelle