After the introduction of the euro in 1999, the debate on the financial stability architecture in the EU focused on the adequacy of a decentralised setting based on national responsibilities for preventing and managing crises. The Financial Services Action Plan in 1999 and the introduction of the Lamfalussy process for financial regulation and supervision in 2001 enhanced the decentralised arrangements by increasing significantly the level of legal harmonisation and supervisory cooperation. In addition, authorities adopted EU-wide MoUs to safeguard cross-border financial stability. In this context, the financial crisis has proved to be a major challenge to the ongoing process of European financial integration. In particular, momentous events such as the freezing of interbank markets, the loss of confidence in financial institutions, runs on banks and difficulties affecting cross-border financial groups, questioned the ability of the EU financial stability architecture to contain threats to the integrated single financial market. In particular, the crisis has demonstrated the importance of coupling to micro-prudential supervision a macro dimension aimed at a broad and effective monitoring and assessment of the potential risks covering all components of the financial system. In Europe, following the de Larosière Report, the European Commission has put forward proposals for establishing a European System of Financial Supervision and a European Systemic Risk Board, the latter body to be set up under the auspices of the ECB. While the details for the implementation of these structures still need to be spelt out, they should reinforce significantly – ten years after the introduction of the euro – the financial stability architecture at the EU level.