After a few years of starts and stops, Christian de Portzamparc's crystalline 400 Park Avenue South (aka the Fortress of Glassitude) finally launched sales in September 2014, and is on track to welcome its first residents by fall 2015. The bottom part of the building holds 269 rentals, developed by Equity Residential, while the top 18 floors hold 81 condos developed by Toll Brothers. Prices for the condos range from $1.5 million to $20 million. The building's shard-like look adds some serious pizazz to the neighborhood—and creates some wacky floorplans. We took a construction tour last fall. [Photo by Will Femia]

The Witkoff Group is in the process of converting the former International Toy Center into 125 high-end condos. Sales launched in July 2013 for its "regular" units, with prices ranging from $3.8 million for a 2BR to $13 million for a 4BR. Then in August 2013, the project brought out the big guns with the launch of its tower of penthouses, which started at $7.5 million. One of the bigger penthouses sold for a whopping $36.5 million, and there is currently another on the market for $35 million.

The Whitman, a condo conversion of the old Plumbers Local 1 building, introduced itself to the neighborhood in February 2013. Since then, big names have flocked to its full-floor residences. Former first daughter Chelsea Clinton and her husband bought in the building, as did racing star Jeff Gordon. Most recently, Jennifer Lopez dropped $20 million on the penthouse.

A landmarked building at 242 Fifth is being converted into four apartments by Pan-Brothers Associates, who are also adding a rooftop addition. In April 2013, the plans won approval from the local community board, and since then, work has been steadily progressing. All four units will have outdoor space, and the Daily News reported that prices will likely "range from about $3.5 million for a 1,600-square-foot pad to nearly $7 million for the duplex penthouse."

In July 2012, L.A. hotelier Sam Nazarian and Moin Development Corp. picked up 444 Park Avenue South with plans to convert the building into an SLS hotel with three bars and restaurants. A few more details were revealed through 2014, and HotelChatter reported that it might open in February 2015, but no official date has been announced. The 190 hotel rooms will have interiors by Philippe Starck.

The office building on Fifth Avenue at the corner of 26th Street, considered the "crowned jewel" of the Ring Portfolio, was sold by megadeveloper Extell to Joe Sitt of Thor Equities in January for a whopping $200 million. Sitt will convert the building into 48 condos including a triplex penthouse.

Another starchitect-designed tower will grace NoMad at the corner of Fifth Avenue and West 30th Street. Victor Homes tapped Rafael Vinoly to create a 51-story condo tower. Only unofficial renderings have surfaced, but they show a slender building with a pretty big cantilever. Demolition permits for the existing buildings were filed in December, but no new building permits are in place.

This hotel has been in the works since 2009, and it's finalyl moving forward. Construction fencing is up at the site, along with a new rendering by Gwathmey Siegel Kaufman architects. It will rise 33 stories and hold 260 rooms.

The Ace Hotel's neighbor at 1182 Broadway has left its troubled past behind, and started its new life as 39 one- and two-bedroom rental apartments. Mocal Enterprises converted the building, and leasing launched a year ago, with prices ranging from $5,800/month to $15,000 for larger layouts on the higher floors.

Handel Architects has filed permits for a 53-story, 825-foot-tall tower with 188 apartments for this site between Madison and Fifth avenues; if approved, the tower will be the tallest structure between Chambers Street and the Empire State Building.

This building's vertical addition led by Kossar + Gary Architects has been in the works for a while, bringing its height up to 17 stories. When complete, the building will have 18 apartments. [Photo via Google Maps]

After gaining their conversion footing with Tribeca's 443 Greenwich Street, developer MetroLoft snagged this commercial building from the bigwigs at Extell—who acquired it as part of the Ring Portfolio—with plans to convert the slender structure on East 25th Street between Park Avenue South and Lexington Avenue into residences. If the developer's work on 443 Greenwich Street is anything to go by, this place will be lovely—and expensive. [Photo via PropertyShark]

Maybe developer Castellan Real Estate got lost, but they don't seem to mind; amidst the neighborhood's pricey condo and chic hotel boom, the developer plans on constructing a slender 21-story tower with 19 affordably-priced, floor-through studios. The building, on 30th Street between Fifth and Madison avenues, will also have ground floor retail and, curiously, one market rate apartment. [Photo via PropertyShark]

One of the few new constructions in the neighborhood, 241 Fifth began sales in June 2013, and sold all 46 condos by April 2014. Developed by Victor Homes and designed by ODA Architecture, the 20-story building's most expensive sale was the top penthouse, which went for $8.15 million.

The community board approved plans for a 23-story hotel at 250 Fifth Avenue in October 2012, but the project has stalled since then. The Department of Buildings says the property currently has a "violation for failure to certify correction of class 1 violation" which sounds bad.

The 141-room Park South Hotel is in the midsts of a $20 million renovation that will modernize its guest rooms, gut the lobby, and add an additional entrance. Owner Atlantic Stars Hotels & Casinos have lured in Boston restaurateurs Tim and Nancy Cushman to "curate" the hotel's food and drink selections, including those for ROOF, it's rooftop bar, which may already be a favorite haunt of Nomad's post-work boozers. [Photo via Park South Hotel]