A stunningly transformed 19th-century carriage house, a true architectural gem in Rittenhouse Square, has hit the Philadelphia market for $3.5 million, writes Abby Montanez for the Robb Report.

Designed by the late, celebrated architect Frank Weise, this striking five-story townhome—once a 19th-century carriage house— is now designated a historic landmark by the city. And for $3.5 million, ...