The iconic tower that has defined Toronto's skyline for over three decades celebrated its 35th birthday on Sunday.

A number of events including a special book signing with tower developers Richard Rohmer and Stewart (Bud) Andrews marked the anniversary of the day the attraction opened to the public in 1976.

For years, the tower was the world's tallest free-standing structure, but was eclipsed by new constructions in Dubai and Asia. The tower currently receives more than 1.5 million visitors per year and generates more than $50 million in annual profit.

Andrews, the man behind the tower's unique design, told CTV Toronto's Scott Lightfoot that he is still very proud of the attraction he helped to build.

"I get excited about it all over again. It's been everything you could expect the tower to be," Andrews said.

He said the structure was originally supposed to have three legs, before he drew the current design and its see-through elevators on a cocktail napkin.

"It didn't really make a hell of a lot of sense, to be going up that high and not enjoy the ride up," he said.

Construction on the tower began in 1973 and took more than 1,500 workers to finish the project. Thousands of people watched from the grounds below as the last piece was laid by a helicopter in 1975.

Jack Robinson, the tower's chief operating officer, was among the crowd.

"People like attractions, especially one that's 1,800 feet tall. This is the thing to do when you come to Toronto," said Robinson.

Changes over the years have included the installation of a glass floor and a lit up tower at night. In the fall, thrill seekers will be able to walk around the outside of the tower in a new attraction called the Edgewalk.

"It's a bit scary, but it really lets you see the city and lets you see all around, it's wonderful," said one tower visitor.

Andrews said that's exactly how he envisioned it.

"It thrills me, there's no question, and I never get tired of looking at it," he said.

With files from The Canadian Press and CTV Toronto's Scott Lightfoot.