Steampunk automaton cat guarding a hidden alley portal

A steampunk automaton giant cat with extremely long ruff, brass gears whirring and clockwork heart ticking, guards a hidden portal in a fog-shrouded Victorian alleyway. Intricate pipework and glowing vacuum tubes adorn its metallic body. The scene is rendered with the detailed, atmospheric quality of dark fantasy concept art, infused with the gritty realism of steampunk aesthetics.