After closing a major funding round last month, D.C.-based tech company Mapbox is more than tripling its real estate footprint.

The location data company signed on for 17K at 740 15th St. NW, and Stream Realty Managing Director Matt Pacinelli, who represented the landlord, said they just reached an agreement for another 4K SF. The company plans to move in early next year.

The new, 21K SF office represents a major step up for the company, which occupies about 6K SF at the Logan Exchange co-working space owned by MRP Realty. In October, Mapbox raised $164M in a funding round led by Japan-based SoftBank, which invested $4.4B into WeWork earlier this year.

"They're growing rapidly," said Pacinelli, who joined Stream Realty in January. "They've gotten a number of rounds of funding recently. It's a pretty impressive group."

The expansion of a homegrown tech company is a good sign for D.C.'s office market, as the District aims to further diversify its economy amid reduced government spending. D.C. was recently ranked the country's No. 3 tech city in a Cushman & Wakefield report, a trend landlords hope will translate into more office demand.

What drew Mapbox to this building most, Pacinelli said, was its historic architectural features. The building was constructed in 1907 and its owner, the National Community Reinvestment Coalition, renovated it recently.

The property sits on the block to the east of Lafayette Square, just north of the White House. The ground-floor retail space features Joe's Seafood and a new bar, Union Trust, from the owners of Solly's and The Pug.