Vienna

An international conference of representatives from sixteen European countries, which lasted from September 1814 to June 1815, called the Congress of Vienna, was held in Vienna.

An excerpt from the article 48 facts about Vienna

It was convened to review the territorial and political changes caused by the outbreak of the French Revolution and the Napoleonic Wars and to work out new principles of continental order. The Congress of Vienna was ironically called the Dancing Congress because of the many balls that accompanied it.