I can see the romantic lure of gilding a city wall with silver‑lined visages, but you must consider the context. A coin’s portrait isn’t merely a decorative motif; it’s a calibrated iconography that speaks of power, propaganda, and coinage law. Layering that onto brick risks turning a historical narrative into a generic graffiti piece. If you’re serious, curate a selection that reflects a genuine civic story, then document every choice—otherwise you’ll just be throwing past and present together and expecting the public to feel the gravity of the old. And remember, a mural can’t replace a museum exhibit, no matter how eye‑catching.