PhiloLabs has released Fable51, an open-source project generating explorable, browser-native 3D reconstructions of real-world locations using autonomous Claude Fable 5.1 agent swarms. The repository contains code to procedurally build detailed digital twins from open data, requiring no game engine or proprietary assets. Two initial worlds are available: Union Square in San Francisco, featuring 129 identified storefronts, working traffic lights, and cable cars, along with interiors for Apple and Nintendo buildings; and Kyoto's Higashiyama district, rendered as a hand-painted anime background traversing 2.3 km of walking routes.

Both projects utilize OSM geometry and USGS elevation data, with validation involving camera-matched viewpoints against real photographs. The codebase provides a full pipeline from reconnaissance and offline asset generation via Blender-as-a-library to a pure Three.js runtime. All generated geometry is derived from Open Street Map and USGS data under open licenses, offering a new approach to procedural urban modeling.