SPRINGFIELD -- MassMutual now has an OK from the Boston Civic Design Commission for its $240 million office tower in the Seaport District.

Following that approval on Tuesday night, the Springfield-based insurer on Wednesday released a fresh set of artist's drawings of what 10 Fan Pier Blvd. is expected to look like. The new drawings reflect small modifications, like changes in sight lines requested by the Design Commission and hammered out between the two sides, said spokeswoman Laura Crisco.

Changes include:

An updated exterior facade:

Enhanced visual interest:

Ground floor plan:

Landscape:

The building will be a multistory office structure with more than 300,000 square feet of floor space. It will be built on an undeveloped parcel owned by MassMutual. MassMutual will be the primary tenant. Boston-based Elkus Manfredi Architects is the designer.

Crisco said there are more approvals necessary before construction can begin. MassMutual has said it plans to be in the offices by 2021.

MassMutual is in the process of consolidating offices and moving jobs to its headquarters in Springfield.

Both moves -- the consolidation in Springfield and the expansion in Boston -- were first announced in February.

The major expansion in Massachusetts is expected to include a $300 million investment and bring 2,000 jobs to the commonwealth over the next four years.

Those 2,000 jobs include 1,500 at corporate headquarters in Springfield and 500 at the new Boston campus. MassMutual plans to spend $50 million on renovations to its headquarters on State Street in Springfield.

MassMutual received a $46 million incentive package from the state of Massachusetts.

The company will close offices just across the border in Enfield, Connecticut, where about 1,500 people work, and most of jobs will move to Springfield.

MassMutual is also closing offices in Charlotte, North Carolina, Somerset, New Jersey, Memphis, Tennessee, and Johnstown, Pennsylvania.

In Boston, MassMutual hopes to create a hub for its high-tech operations and make use of the highly skilled workforce congregating there. The Fan Pier offices eventually will grow to 1,000 employees, the company said.

"We look forward to growing our presence in one of the state's most exciting and vibrant areas and building our campus at Fan Pier, which will be a standout piece of architecture in the city," said Roger Crandall, chairman, president and CEO of MassMutual, in a news release. "Our location in the Seaport will offer our employees proximity to the city's amenities, allow us to tap into its expansive talent pool and innovative spirit, and better position us to best serve our policyowners for generations to come."