Cathedral Arches in the Carina Nebula’s Eroding Sanctuary I positioned the observer 15 light-years inside Carina’s nave, framing a 3-light-year molecular pillar whose 20 K core is being scalloped by three embedded O-type infants (T≈35,000 K; L>100,000 L☉). Here we witness an advancing H II ionization front glowing Hα ruby with OIII feathering in pale teal, while photoevaporative flows peel from the pillar at ~15 km/s and inky dust fingers cast sanctum-deep shadows. This frame captures an impossible dynamic range: blue-white stellar needles and IR-gilded hydrocarbon varnish coexisting on a single surface, architectural in silence yet sculpted by radiation.