The new owners of the former Barnes & Noble building in Boston’s Downtown Crossing plan to begin renovations of the 77,000-square-foot structure and has hired Colliers International as leasing agent to fill six floors of office and retail space.

L3 Capital and LaSalle Investment Management closed on the acquisition Wednesday and announced the rebranding of the property as DTX 399, a nod to its street address at 399 Washington St.

Anchor tenant Barnes & Noble closed in 2006.

The redevelopment, beginning this summer, will add a “sleek, contemporary” new look to the bottom two floors and update building systems, Colliers announced today.

“Given its proximity to the Millennium Tower and the exciting tenants who accompanied that ‘game-changing’ project, we anticipate tremendous interest from flagship retailers and innovative companies drawn to the vibrancy and accessibility of DTX,” Colliers Senior Vice President Peter Montesanto said in a statement.