Representatives of WS Development, Amazon and others gathered to celebrate the start of construction on the e-commerce giant's 17-story Boston tower. Photo by Steve Adams | Banker & Tradesman Staff.

Attendees unleashed a shower of yellow confetti as developers and officials marked the groundbreaking of Amazon’s future 430,000-square-foot offices in Boston’s Seaport District.

The 17-story, 525,000-square-foot office tower at 111 Harbor Way is the first new construction of office space for Amazon as it expands its local workforce by 2,000 jobs. Scheduled for completion in the second quarter of 2021, it will generate 2,000 jobs in machine learning, speech science, cloud computing and robotics engineering.

“The only time in the city’s history that Boston has grown at a faster pace than what we see today was during the urban renewal programs of two generations ago,” said Yanni Tsipis, senior vice president at WS Development. “Today we’re fortunate we don’t have to tear down big blocks of our city just to realize this basic growth like we did 50 years ago. Today’s extraordinary economic growth is organic, it’s foundational and it preserves economic opportunities for all Bostonians from Orient Heights to Oak Square to Uphams Corner to right here in the Seaport.”

Designed by Gensler, the 17-story tower contains 430,000 square feet of office space with outdoor terraces on alternating floors, and two stories of retail space totaling 81,000 square feet.

Designed by Gensler, Amazon’s 17-story tower contains 430,000 square feet of office space with outdoor terraces on alternating floors, and two stories of retail space totaling 81,000 square feet.

The groundbreaking coincides with construction of the Harbor Square Park, part of a planned one-third mile public space leading from Summer Street to Seaport Boulevard designed by James Corner Field Operations.

A $5 million, 15-year tax agreement with the city of Boston requires Amazon to create 2,000 local jobs by 2025.

Mike Touloumtzis, Amazon’s Boston-area site leader, estimated the company’s economic impact including infrastructure and payroll at $3.6 billion.

The Seaport parcels owned by WS are approved for 7.6 million square feet of development including 3 million square feet of office and lab space, of which 1.5 million square feet available. Amazon has an option to lease a second office building on an adjacent parcel, but has not yet exercised it, Tsipis said.

Citizens Bank and CIBC provided construction financing for the project.