The South Boston waterfront was long a bleak area separated from the rest of the city by the Fort Point Channel, its docks and warehouses recalling a faded shipping past. Now, rechristened the Seaport district, construction cranes dot the landscape as builders put up high-end condominiums, offices and hotels in one of the biggest neighborhood transformations in Boston history.

“The waterfront is an overnight success that’s taken nearly 30 years to come to fruition,” said Brian Kavoogian, president and founder of Charles River Realty Investors LLC, which has developed or acquired more than 20 million square feet (1.9 million square meters) of real estate in the Boston metropolitan area. “It finally reached a tipping point.”

Boston’s real estate market, often overshadowed by the skyscrapers of New York and government-fueled growth in Washington, is seeing a boom in construction as developers financed with cheap debt seek to profit from a growing workforce of educated, young adults and strength in the technology and life-sciences industries. The office-vacancy rate is among the lowest of major U.S. markets and tenants are occupying new space at almost triple the national average.

Construction spending in Boston increased an estimated 37 percent in the year ended June 30 to $3.83 billion, the most since 2008, according to the mayor’s office. The market is hot enough that some developers are considering building offices without having landed anchor tenants.

“You have a city that has biotech and other thriving industries, and some big-name financial services,” said John Garth, managing director at Pembrook Capital Management LLC, a New York-based real estate investor looking to finance apartment construction in Boston. “It’s a huge draw for young people, and that creates lots of demand for rental apartments as well as new office space and other construction.”