The object is a commemorative plaque created to mark the completion of the Eurasia Tunnel, one of the most significant underground infrastructure projects of the 21st century. The plaque is housed within a finely crafted wooden presentation case, reflecting both durability and timelessness, qualities intentionally aligned with the long-term legacy of the project it represents. At the center of the plaque is a circular, gold-toned metal medallion featuring an abstract yet symmetrical relief pattern. This motif symbolically evokes depth, continuity, and layered structure—concepts intrinsic to underground engineering and geotechnical science. The circular form represents unity and connection, directly referencing the Eurasia Tunnel’s role in linking the Asian and European continents beneath the Bosphorus. Below the medallion, an engraved metal plate bears an inscription in Turkish identifying the project as “Avrasya Tüneli En Derin Nokta Anısı” (Eurasia Tunnel – Deepest Point Memorial), dated December 20, 2016. The text situates the object at the deepest section of the tunnel, emphasizing the exceptional engineering conditions under which the structure was realized. Institutional logos engraved on the plate represent the key organizations involved in the tunnel’s design, construction, and operation, underscoring the collaborative and multidisciplinary nature of the project. Materially, the combination of natural wood, metal, and precise engraving reflects the intersection of craftsmanship and advanced engineering. Conceptually, the plaque transcends its function as a ceremonial object. It serves as a physical record of a century-old vision brought to life through modern geotechnical knowledge. Moreover, rosettes, also the symbol of the Eurasia Tunnel, are just one of the main patterns that the great architect Sinan loved to use in his buildings in İstanbul.