TD Garden is undergoing its first major expansion since the Boston arena opened in 1995. The privately owned Delaware North, its owner and operator, is sinking $100 million into the home of the Bruins and the Celtics to expand it by a total of 50,000 square feet. (Jeremy Jacobs, CEO of Delaware North, owns the Bruins.)

The expansion also comes amid the ongoing 1.5 million-square-foot Hub on Causeway development at the site of the old Boston Garden across the street—a project that Delaware North is undertaking with Boston Properties. Taken together, the two projects are transforming the area around North Station where the North End meets the West End.

Here below are some before-and-after images, courtesy of Delaware North, of how certain parts of TD Garden will look post-expansion. The expansion is expected to take up to two years, with parts such as the new entrance and a pedestrian tunnel connecting the Green and the Orange lines to commuter rail opening in December.

We start with how that entrance will change, including via an atrium with a glass canopy and two new escalators.

Now here’s a planned members-only party deck on the ninth level called Rafters.

Below is a before-and-after of the planned Rafter Studios, spaces that will accommodate from 20 to 200 people on the ninth level of the arena.

Larger concourses are a big part of the expansion. These are before-and-afters for concourses on Levels 4 and 7.

The two-level, 7,500-square-foot 1928 Club will be a new venue for Club Seating clients.

Society Kitchen + Tap will supplant the Premium Bar and Grille on Level 5.