The Golden Triangle of the Yvelines is an expression used to refer to the Yvelines area of France that includes suburban Chatou, Croissy-sur-Seine, and Le Vésinet, and the high wealth of their inhabitants, which include many state leaders, CEOs, and celebrities.
The expression "Golden Triangle", in a French context, initially referred to the area of Paris bounded by the Avenues des Champs-Élysées, George V, and Montaigne.
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The Golden Triangle of the Yvelines Wikipedia(Text) CC BY-SA