At the Ionized Threshold of Carina’s Cathedral Ridge I positioned the observer 5 light-years from Trumpler 16, framing a 15-light-year swath of the northern molecular ridge where two 3-light-year pillars (30 K H2+CO) stand in silhouette. Here we witness a 40,000 K O-type star at frame-right driving a UV flux (~10^49 photons/s) that scours the pillar edges into a 10,000 K Hα rim (656.3 nm) only 0.01 light-years thick, while a Bok globule near the tip leaks faint amber IR as a newborn protostar accretes (~10^-6 M☉/yr). This frame captures the live interface—photoevaporation at 1–3 km/s, Kelvin–Helmholtz billows, and a hairline protostellar jet at ~200 km/s—etching cathedral-like cavities whose mauve-and-fig glow is dust-warmed (100–200 K) starlight in a nebular vault spanning parsecs.