Clark Construction has celebrated a construction milestone of the 600 Fifth Street NW office building in Washington, D.C., US, with a topping-out ceremony.
The joint venture between Rockefeller Group and Stonebridge, alongside Clark, celebrated the event.
Kendall Heaton Associates is serving as the architect while Clark is the general contractor.
International design architect Pickard Chilton planned the redesign of the project.
The design of the building includes the addition of four new storeys and open-air terraces on alternating floors to enhance natural light and air for occupants.
The building's exterior has been redefined with a new energy-efficient glass curtain wall while a public park at the ground level has been added.
The 600 Fifth Street NW project is said to be the only new office building currently under construction in Washington, D.C.. It is set to be delivered within the next two years.
The building comprises 400,000ft² of space and is being constructed on the site of the former Metro headquarters.
During the topping-out ceremony, the highest steel piece was placed, paving the way for a 12th-floor tenant-amenity space with 15ft ceilings and outdoor terraces.
To date, the construction team has installed more than 747 tons (t) of structural repositioning steel, 1,073t of overbuild steel on the existing structure, and poured 3,700 cubic yards of concrete.
Moreover, it has removed more than 9,800t of debris from the site.
Clark division president Terry Simon said: “This milestone would not be possible without the strong partnership between Rockefeller Group, Stonebridge, Clark and the talented design and trade partners on this project.”
Last June, Stonebridge and Rockefeller Group secured a 99-year ground lease with Metro and commenced the $375m construction project.
The 600 Fifth Street NW office building is already 50% preleased.
In 2023, international law business Crowell & Moring signed a long-term lease of about 199,000ft² for its D.C. headquarters, becoming an anchor tenant of the building.
