Much of the city's skyline is changing dramatically, with Downtown Brooklyn perhaps no better example of that trend, but much of the growth has been in high-rise residential buildings. On one quiet lot, that is about to change in a big way. NY1's Josh Robin filed the following report.

For decades, an area of Downtown Brooklyn was a parking lot and houses of indeterminate age. Over a couple of years, a 40-story office building could sprout, another sign of Downtown Brooklyn transforming.

"Look around you," said Alicia Glen, deputy mayor for housing and economic development. "This neighborhood was rezoned almost 10 years ago in order to encourage high-density residential and commercial development, because we think there are places in this city of New York, a global city, where density and height are very appropriate."

A map reveals just a few new developments, with a picture showing a recent rendering of 340 Flatbush Avenue Extension, to be Brooklyn's tallest. The architecture is changed, though a new picture isn't yet available.

Monday marked the dedication of the first ground-up commercial space, a sign of the residential market's growing heat.

In Downtown Brooklyn, the price of commercial real estate is about $20 a square foot less than the price of residential real estate. The city wanted to build commercial on this site, and it used some leverage that it got from an adjacent site.

The city is building a park and underground garage. It transferred the air rights - the unused space - to the new building, allowing it to more than double in height. Experts expect more offices to follow.

"A lot of people are waking up to the commercial office opportunity in Brooklyn," said Tucker Reed of the Downtown Brooklyn Partnership. "You're seeing it in Williamsburg. You're seeing all the growth that's happening down in Industry City."

"When you have 15,000 apartments going up, it then leads you to the commercial part," said real estate developer Bobby Dweck. "Whereas if you did office first, you'd have 9 to 5, and there would be no neighborhood."

Is it too much? Families United for Racial and Economic Equality, or FUREE, says so. In a statement, they said, "FUREE believes that the Department of City Planning does not engage in planning that truly measures and accounts for the future needs of communities but rather for real estate development. The city’s affordable housing crisis can’t be solved by simply making our neighborhoods more dense with market-rate housing without addressing the inherent pressures to that logic which encourage displacement of lower-income residents."

Officials noted that the rezoning is a decade old.

"I'm just really happy here today to be able to say it's actually accomplishing, through our work, the very objective, which was to have a mixed-use district," Glen said.