Rittenhouse Square is the densest single block of urban canopy in the Northeast. The London plane trees that ring it were planted in 1913 by Paul Cret, the same Beaux-Arts architect who laid out the diagonal paths and the central fountain. They have been there long enough now that the four interior paths are continuously covered, the perimeter sidewalks are mostly covered, and on a hot July afternoon the square reads — by the city’s own measurements — six to eight degrees below the surrounding streets. There is no better urban shade in the city.
A mile east, the old colonial district around Independence Hall holds a different kind of cover: low brick rowhouses with deep recessed entries, the long brick arcade behind Carpenter’s Hall, and the planted lindens along Walnut and Locust. None of it is as dense as Rittenhouse, but stitched together with the squares (Washington Square, Independence Square, the courtyard of Old St. Joseph’s) the walk holds. The picks below all string these two systems together, using the Walnut Street axis as the spine.
A note on Walnut itself: the trees on the north sidewalk are healthier than the ones on the south, which lost a row to a streetscape project in the early 2000s. The north side is also the building-shadow side from about 1 PM onward, which compounds the advantage. Walk on the north.