The developer of one of the most significant office-to-residential conversions in D.C. has revealed new plans calling for more than 500 units on the site.

Philadelphia-based Post Brothers filed plans last week to the local Advisory Neighborhood Commission showing it aims to add multiple floors to the former Universal North and South office buildings, reaching a height of 120 feet. It is scheduled to present the plans at a Dec. 21 meeting.

The properties, located at 1825 and 1875 Connecticut Ave. NW in the Dupont North area, would retain an internal parking structure and are slated to have roughly 440 parking spaces after redevelopment.

The parking structure would be topped with a multilevel exercise facility including an indoor pool, which would front an internal garden.

The property would also feature ground-floor retail, a new lobby and a coworking lounge.

Post Brothers acquired the Universal North and South buildings for $200M in April.

The development is Post Brothers' first in the District. President and co-founder Matthew Pestronk, speaking at Bisnow's Multifamily Annual Conference in D.C. on Nov. 29, said the opportunity at the former Universal North and South building site was too good to pass up.

"The city needs to have 20 to 30M SF of office changed into another use, and to me that single thing represents the biggest opportunity set," Pestronk said. "Office conversions everywhere are the biggest opportunity set any of us will see in our lifetimes."