645 Congress is owned by Bayside Maine LLC with project management by Shinberg Consulting LLC.

Bayside Maine, LLC has completely renovated 645 Congress, converting it into 56 new apartments with modern amenities and a brand new facade.

The existing Main Building at 645 Congress Street, which was previously used as a dormitory with cafeteria and offices by the University of Southern Maine, has been given a new interior and approximately 11,000 square feet of ground floor retail space.

The three buildings known as the A Wing, B Wing and Yankee Clipper Wing, located towards the north and rear of the property, have been demolished. In their place is a surface parking lot and green space.

The Main building that faces Congress Street was constructed in two phases. The older six-story section was built around 1895 while the five-story section to the east was finished around 1900.

Originally built as a rooming house and then converted into the Columbia Hotel, the buildings functioned primarily as a hotel or motel for the last century before the University converted it to a dormitory in 1988.