SEATTLE (AP) — Tourism is booming in Seattle. Just take a look at the Space Needle.

The family-owned landmark is set to unveil the biggest renovation in its 56-year history next month, a $100 million investment in a single year of construction that transformed the structure's top viewing level with floor-to-ceiling glass.

Seattle and King County benefited from $7.4 billion of spending by a record 40 million visitors last year, a number that has grown annually since the 2008 recession, according to Visit Seattle, a nonprofit advocacy group for the tourism industry.

Dozens of cranes that have become a mainstay of the city's skyline over the past decade aren't just building apartments and offices, but hotels to absorb the flood of arrivals at Seattle Tacoma International Airport.

"The environment is friendly with this type of investment. It wasn't a difficult thing at all to obtain financing," said Ron Sevart, president and chief executive officer at Space Needle LLC. "What we like to say is trends last 50 years. What this investment is more about is the next 50 years, and making sure the space needle stays relevant."

Hyatt Hotels Corp. is building a 1,260 room tower that's set to become the biggest hotel in the Northwest when it opens in the fall. In 2017, SeaTac Airport bucked the second year of declines in international arrivals to the U.S., posting a 5 percent increase, according to Visit Seattle.

Seattle's Wright family, which built and owns the Space Needle, is also installing glass in the observation deck's rotating floor and remodeling the restaurant in the first phase of the renovation.

Repainting the exterior of the 600-foot (183-meter) structure and replacing its three elevators will follow, according to Karen Olson, chief marketing officer at Space Needle. The project is being finance with a commercial loan, she said.

"Keeping your product well maintained and 'fresh' increases desirability," said Jeanne Liu, senior vice president of research at Longwoods International USA Inc., a consultancy that compiles tourism industry statistics for Visit Seattle. "There are a lot of places to visit in this world, and those destinations with a solid tourism infrastructure that is well maintained can use that as a competitive advantage."