The Seaport’s notably elliptical tower has landed its first tenant.

Needham-based technology company PTC announced Thursday it will move its global headquarters to 121 Seaport in Boston’s Seaport District. The firm will take 250K SF in the Skanska-developed building.

“This is a win for the region as PTC looks to retain its existing talent while continuing to build their brand and company within our growing innovation economy in Boston,” Boston Mayor Martin Walsh said in a prepared statement.

Skanska expects to deliver the 17-story, 400K SF building in Q1, but PTC will not move into its offices on the top nine floors until early 2019. Newmark Knight Frank represented Skanska, and Cresa represented PTC in the deal.

“121 Seaport’s design, amenities and location made the selection of our new global headquarters an easy one,” PTC CEO Jim Heppelmann said in a statement.

More than 1,000 employees will move from PTC’s current home at 140 Kendrick St. in Needham. 121 Seaport has already garnered acclaim for ditching the Seaport’s stereotypical glass-box architecture for an elliptical design. Skanska has also touted its large floor plates, two floors of retail and Boston Harbor views to potential tenants.

It was previously reported that Aetna had toured the building when looking to move its corporate headquarters from Hartford, Connecticut. The insurance company eventually decided to move to New York City.