This dissertation explores the relationship between international financial markets, financial frictions, and the real economy. In particular, the dissertation focuses on the role of the United States of America (US) as the key country in the global financial architecture. The research presented here advances the study of international finance and macroeconomics by analyzing how the combination of two factors, the greater financial development of the US and financing frictions, leads to the special global roles of the US funding markets and the US dollar. In the first Chapter of the dissertation, I develop a model of financial intermediation in a closed economy, which is also the key building block of the open economy analysis in the second Chapter. In an economy with savers and financial intermediaries where financing frictions are present, the state of the financial sector becomes the key state variable. The financing frictions, modeled as the limited enforceability of deposit contracts, prevent capital from flowing freely from savers to the financial intermediaries that ultimately allocate capital to productive real assets. When financial intermediaries are well capitalized, their capital acts as a safety buffer for potential investment losses and, consequently, financing frictions are alleviated. In this state of the world, financial markets closely resemble those of the standard frictionless asset pricing framework. When, on the other hand, intermediaries are poorly capitalized, concerns for potential losses of capital disrupt the financing markets. In this state of the world, capital does not flow smoothly from savers into productive assets via financial intermediaries. In general, risky assets' prices fall and their volatility increases, thus replicating typical features of financial crises. Interestingly, these effects are highly non-linear. In the second Chapter, I provide a framework for understanding the global financial architecture as an equilibrium outcome of the risk sharing between countries with different levels of financial development. The country that has the most developed financial sector takes on a larger proportion of global fundamental and financial risk because its financial intermediaries are better able to deal with funding problems following negative shocks. This asymmetric risk sharing has real consequences. In good times, and in the long run, the more financially developed country consumes more, relative to other countries, and runs a trade deficit financed by the higher financial income that it earns as compensation for taking greater risk. During global crises, it suffers heavier capital losses than other countries, exacerbating its fall in consumption. This country's currency emerges as the world's reserve currency because it appreciates during crises and so provides a good hedge. The model is able to rationalize these facts, which characterize the role of the US as the key country in the global financial architecture. In the third Chapter, I provide empirical evidence on the role of the US dollar as a global safe asset. This empirical evidence provides one of the stylized facts analyzed in my theoretical work. I show that the US dollar earns a safety premium versus a basket of foreign currencies and that this premium is particularly high in times of global financial stress. These findings support the view that the dollar acts as the reserve currency for the international monetary system and that it is a natural safe haven in times of crisis, when a global flight to quality toward the reserve currency takes place. During such episodes, investors are willing to earn negative expected returns as compensation for holding safe dollars. I estimate the time varying dollar safety premium by using instrumental variable techniques to condition information down.