One of the most prominent and challenging works left by the Ottoman scholar and polymath Katip Çelebi is his massive geographical work, the Cihânnümâ, which was never completed. The noted Ottoman founder of its first printing-press, Ibrâhîm Müteferrika, considered it important enough to expand upon its foundations and print the work in 1732. The development of the Cihânnümâ is remarkable, at least in part, because Katip Çelebi recognized the utility of several treatises of European geographical literature that had been emerging in the sixteenth and seventeenth century. Having had these works translated by intermediaries, he was in the process of rewriting the work with the input from this foreign literature when he died in 1657. While the work has since attracted the attention of a number of German scholars, interest in it has otherwise languished in favor of Katip Çelebi's other, more accessible works, such as _The Balance of Truth_ or his catalogue of medieval and early modern works of Islamic civilization. The goal of this paper is to examine how Katip Çelebi interpolated discussions of European expansion throughout the world into the structure of the Cihânnümâ. In particular, this paper hopes to focus on the author's discussion of Spanish exploratory and expansion-based missions into the regions of the Western hemisphere. Specifically, the printed text of the Cihânnümâ focuses on the figures of Christopher Columbus and Ferdinand Magellan as critical figures in this process. Through an examination of these chapters of the work, and perhaps others, the paper will address the question of the extent to which an Ottoman intellectual like Katip Çelebi appreciated the impact and importance of European maritime expansion on the global history of his times.