Welcome to Ultimate Homes, a new Robb Report video series in which host Mark Ellwood guides you through the most striking and luxurious homes on the prime market today. Whether it’s a three-story condo in a New York high-rise or a sprawling oceanside estate on the cliffs of Malibu, we’ll show you every room—and amenity—inside the world’s most coveted addresses.

Miami is an energetic city in constant flux, whether it’s the ocean tides that roll in and out every day, the tourists checking in and out of glamorous hotels, or the revitalization of urban neighborhoods. For decades, downtown’s Brickell Avenue was famously known as “Millionaire’s Row,” lined with 19th-century mansions surrounded by tropical gardens. Today, the street has been thoroughly modernized, replaced by a gleaming forest of glass towers housing spacious condos with bird’s-eye views and sky-high prices.

Spanning the entire 54th floor of the sinuous Echo Brickell is one such mansion in the sky, this one a sophisticated assemblage of high-quality finishes and bold design. The penthouse condo measures about 4,200 square feet, comprising a careful balance of vast spaces for entertaining and more cozily proportioned spaces for quiet tête-à-têtes.

The elevator opens to the foyer, where 12-foot ceilings and polished stone floors lead into the massive great room, stretching 80 feet long; there’s plenty of room to accommodate a trio of lounging and dining areas. A wall of full-height glazing connects to one of four glass-railed terraces, while thick structural columns are sheathed in mirrors that render them almost invisible. The long central island’s polished quartz surface lights up from within, giving the kitchen a touch of soft glamour, and an adjoining area can be utilized as a lounge or casual dining space.

Peppered throughout are smaller spaces that include a library, where the soaring ceiling and full-height timber shelving belie the petite footprint (the fabric on the walls and the marigold chairs are from Fendi Casa), while a color-soaked snug for watching TV has felted wallcoverings and the chaotically patterned cult-favorite Mah Jong sectional sofa by Roche Bobois.

Monthly maintenance costs are about $9,600 with annual taxes of around $75,000. The penthouse is currently available at just under $17 million with Lourdes Alatriste of Douglas Elliman.