Commissioned by Mahmud I and centered around an ambitious mosque, the history of the Nuruosmaniye Complex in Istanbul remains fraught with unresolved questions regarding its radical architectural and urbanistic innovations. Surprisingly, despite being the earliest example of the so-called Ottoman Baroque, the complex already encapsulates the full range of innovations that would define the new aesthetic norms of the following decades. Moreover, compared to later sultanic commissions, such as the Laleli and Ayazma complexes, it demonstrates the most crystallized and systematic use of an architectural language that was still in the process of being defined. This seemingly paradoxical situation is particularly evident in the mosque, where, instead of a gradual maturation, the new ideas were boldly introduced from the outset. The Nuruosmaniye Complex marked a turning point in urbanistic, architectural, and decorative experimentation. While some of its innovations quickly became recognizable leitmotifs of the period, others remained unique and did not reappear in later constructions. Among these unique features are the polygonal courtyard, the elimination of the ablution fountain as a freestanding structure, the unprecedented volumetric arrangement of the upper gallery in the prayer hall, the lavish cornice with a hollow and walkable section, the continuous calligraphic decoration following the perimeters of the space, and the asymmetrical C-shaped royal pavilion. These elements were skillful responses to an increasingly felt need for change in Ottoman mosque-building conventions, and the final outcome was highly praised by both local and foreign contemporaries. So, why were some of these innovations fully adopted while others were abandoned? This paper aims to critically analyze the experimental features introduced at the Nuruosmaniye Complex, which, despite their initial appearance, were not adopted in subsequent Ottoman mosques. By situating these innovations within a broad chronological, sociocultural, and artistic context, the study seeks to provide new insights into the building dynamics and professional networks of the period. Additionally, it will challenge longstanding assumptions about the limits of architectural innovation in Ottoman mosque construction. Why were these novelties only implemented in the complex of Mahmud I? Where did they originate, and why did they remain as isolated attempts? To address these questions, the paper will combine thorough architectural analysis with archival evidence and the observations of contemporary commentators.