Society Hill
Towers

Three identical apartment towers rise from a shared plaza two blocks off the Delaware, the centerpiece of the Washington Square East urban renewal plan, won in competition by developer Webb & Knapp with a young I. M. Pei as architect. Completed in 1964, they put a modernist exclamation point on a neighborhood of 18th-century rowhouses, and the pairing still defines Society Hill's skyline.

The facade is the structure: a load-bearing egg-crate of cast-in-place concrete on a six-foot module, with floor-to-ceiling aluminum-framed windows set deep into the grid. At the base the grid lands on a colonnade of slender columns around a recessed glass lobby. On the plaza stand Leonard Baskin's bronze Old Man, Young Man, The Future (1966) and, to the west, 37 flat-roofed brick townhouses Pei designed as the towers' low-rise counterpoint.

Every other building is extruded from its real OpenStreetMap footprint at its LiDAR-measured height: about 2,800 in detail around the towers, and hundreds of thousands more across the whole city from the Northeast to the airport. Roughly a quarter-million heights come from Philadelphia's 2022 aerial LiDAR survey (City of Philadelphia building footprints; USGS/NOAA point cloud), and in the Society Hill core the roof forms themselves are measured from the same flight: gable, hip, ridge direction, eave and ridge heights. Facades draw on the city's property records (OPA): each building's construction era, material, storefront use and story count pick its brick, siding, schist or curtain-wall dress and its true window rows, and every roof wears the color sampled from the city's 2024 aerial orthophotos. The blocks you walk (and fly over) are the blocks that are there.

The forest is real too: every street and park tree in the modeled area comes from Philadelphia Parks & Recreation's 2025 tree inventory via OpenDataPhilly, each one at its surveyed spot, sized by its measured trunk and shaped by its species; tap a canopy to learn what it is. The bronze inlays on the ground trace the city's registered historic districts, Society Hill first among them, and the neighborhood names that appear as you climb come from the city's neighborhood boundaries (CC-BY). Historic districts and neighborhoods: City of Philadelphia / OpenDataPhilly.

Served outside the artifact sandbox, the city also moves: SEPTA's real-time feed drives every tracked bus and street trolley through the streets at its live position, snapped to its street and refreshed every few seconds. Buses fly the SEPTA badge, trolleys a green pin; tap one (or search a route number) for its route, destination and how late it's running. Indego's bike-share docks are live as well: every station's racked bikes, classic and electric, with counts refreshed each minute; tap a dock for its station. The Market–Frankford El rides its steel viaduct from the Callowhill portal to Frankford, though trains are not shown: SEPTA publishes no usable live positions for its rail lines, so rather than guess, the model keeps to what's real. Car traffic follows the same honesty rule from the other side: no public feed of live car positions exists, so the Typical Traffic layer synthesizes cars at each street's real measured volume (PennDOT annual average daily traffic), swelling through rush hour and thinning to a true one-to-one count in the small hours — typical flows for the clock's day and time, never claimed as live. Vehicle positions: SEPTA real-time API. Bike share: Indego (City of Philadelphia / Bicycle Transit Systems). Weather: Open-Meteo. Address search: OpenStreetMap Nominatim. Live flights: adsb.fi community ADS-B data. Live ships: AIS via aisstream.io. SEPTA and the SEPTA logo are trademarks of the Southeastern Pennsylvania Transportation Authority, and Indego is a service of the City of Philadelphia; this unofficial model is not affiliated with or endorsed by either.

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Outside claude.ai’s sandbox the sky also follows the real Philadelphia weather: live cloud cover and wind via Open-Meteo, refreshed every 15 minutes (the ☁ figure in the time panel).