On 1 December 1998 the European Central Bank (ECB) was officially established in Frankfurt am Main as the central bank for the member states of the European Union that would adopt the euro. The ECB’s creation followed years of treaty negotiation and preparatory work under the Maastricht Treaty (formally the Treaty on European Union), signed in 1992, which set out the roadmap for Economic and Monetary Union and the eventual introduction of a single currency. The ECB inherited responsibilities from the European Monetary Institute (EMI), which had been set up in 1994 to coordinate monetary policy preparation among EU central banks. With its formal founding in December 1998, the ECB assumed responsibility for conducting the single monetary policy for participating member states, managing foreign reserves for the euro area, and ensuring price stability. Its primary mandate, as established by the EU treaties, is to maintain price stability in the euro area, giving it operational independence from national governments. The establishment of the ECB was accompanied by the formation of the European System of Central Banks (ESCB), which comprises the ECB and the national central banks of all EU member states. Initially, that structure provided a framework through which the ECB could work with national central banks in the preparatory phase and later, once a country adopted the euro, as part of the Eurosystem (the ECB plus the national central banks of euro-area countries). The ECB’s Governing Council—composed of the Executive Board and the governors of national central banks of euro-area members—became the institution’s main decision-making body for monetary policy. The ECB’s founding was a legal and institutional milestone rather than the immediate start of euro cash circulation. The euro as a unit of account had been introduced for non-cash transactions on 1 January 1999, when eleven EU countries fixed their exchange rates irrevocably and the ECB began setting a single monetary policy for them. Euro banknotes and coins entered circulation later, on 1 January 2002. From its inception, the ECB operated with a mandate centered on price stability, using conventional and, in later years, unconventional monetary policy tools to pursue that goal. The creation of the ECB reflected broader political and economic integration within the European Union and was accompanied by debates over central bank independence, democratic accountability, and the balance of responsibilities between national governments and supranational institutions. Over subsequent decades the ECB’s role expanded in response to crises—most notably the sovereign debt crisis of the 2010s and the COVID-19 pandemic—when it adopted a range of measures, including large-scale asset purchases and targeted lending programmes, to preserve the functioning of the monetary union and support price stability. Institutionally, the ECB established its headquarters in Frankfurt, a city with historical importance for German and European finance. Its legal basis and powers derive from the Treaty on the Functioning of the European Union (TFEU) and the Statute of the European System of Central Banks and of the European Central Bank. As a result, the ECB is accountable to the European Parliament and reports regularly to the European Council and the Council of the European Union, while retaining operational independence in pursuing its monetary-policy mandate. The formal establishment of the ECB on 1 December 1998 is thus a key date in the history of European monetary integration: it marked the institutional readiness of the eurozone to operate a single monetary policy and set the stage for the euro’s later public introduction and the ongoing evolution of the euro area’s economic governance.