In the early 20th century, Philadelphia's Horace Trumbauer was the go-to architect for America's newly rich industrial barons. When he wasn't designing their classically inspired townhouses and country retreats, he was providing them with grand hotels to stage their fancy balls. The largest and most ornate of these was the Benjamin Franklin Hotel at Ninth and Chestnut Street.

The massive, E-shaped building opened in 1925, just in time for the sesquicentennial celebration, with 1,200 hotel rooms, a gilded ballroom (featured in the movie Silver Linings Playbook), and a triple-vaulted dining room. But the space that left you gasping was the lobby, which sprawls across the better part of the block.

Elements of the decor resemble a private library, the kind you might find in one of Trumbauer's country houses, but rendered on a colossal scale. The spectacular crimson-and-gold plaster ceiling was inspired by the pictorial imagery of Josiah Wedgwood's 18th-century pottery and includes an interlocking puzzle of rosettes, sunbursts, and nymphs on horseback. Trumbauer contrasted the excess with a marble checkerboard floor that reflects the light of the crystal chandeliers upward.

The glamour didn't last long. After the 1929 stock market crash, the hotel went into decline, becoming dowdier and dowdier. A 1990 renovation to convert the hotel to apartments only made things worse, especially when the new owners painted the ceiling blue and orange. Fortunately, the building was rescued in 2011, when it was bought by Korman Associates, which owns a chain of long-stay hotels called AKA.

Korman hired Stanev Potts Architects to restore Trumbauer's lavish details, and the lobby is once again the grandest in the city. Because the Franklin is now a mixed-use building with offices, apartments, and retail, Korman had Stanev Potts partition the lobby to serve the three constituencies. Carving up such a symmetrical, fully realized composition is not ideal, but the architects trod lightly, using opaque glass screens to separate the residential lobby from the office access. Amid the sparkle of the chandeliers and the excellent lighting design by New York's Fisher Marantz Stone, the screens almost disappear.

One downside is that the main space is accessible only to residents and their guests. Fortunately, there is a work-around for the public. The original hotel reception desk has been turned into a lobby bar for the The Rarest, a new restaurant on the Chestnut Street corner. To give this part of the lobby its own identity, Stanev Potts covered the bar's curved ceiling in reflective gold paint and installed a wall of vodka bottles, creating a glowing oasis from which to admire the glory of Philadelphia's jazz age. Short of renting an apartment, it's the next best way to experience Trumbauer's magnificent lobby.