The breakup of the eurozone appeared likely in the aftermath of the Global Financial Crisis (GFC), while the European Union (EU) has long been modeling regional integration for East Asia. Recognizing different political–economic contexts between East Asia and the EU, what can we learn from the experiences of the eurozone so far? This chapter tries to answer the question by examining regional financial integration in the two regions from the viewpoint of international macroeconomics. Financial globalization since the 1990s has played the key role here. We can summarize our observations as follows: East Asia’s fundamental strength shown throughout the GFC implies weak motivation to promote further regional financial integration toward a monetary/fiscal union like the EU. The global sudden stop of capital inflows due to the GFC seriously damaged vulnerable links in the eurozone, although crisis-driven policy innovations seem to strengthen its macro-financial policy framework. As to the future role of the eurozone, at issue is the volatility intrinsic to the global financial market, which would aggravate the asymmetry across currencies, potentially harming resource allocation and growth. Post-Bretton Woods (BW) flexible exchange rates did not wipe away but magnified this asymmetry (i.e., US dollar dominance). The euro and eurozone could challenge this fundamental flaw in the present international monetary system.