Apple is nearing completion of its new "spaceship" headquarters in northern California.The company has been secretive about the project,just as it is about its new product development.But Apple officials have said they plan to move into the new headquarters in 2017.Reuters news agency quotes people involved with the projectas saying the move could happen as early as this spring.Construction began in late 2013and the cost of the project is estimated to be at least $5 billion.The building is located in Cupertino, California,near Apple's current headquarters.Many people have compared the design and constructionto the way Apple has developed its most successful products.These methods include extreme attention to detailand creating visually pleasing features.Apple employees and people involved in the constructionhave not said much publicly about the project.However, some employees did tell Reuters that one iPhone design themefound throughout the building is rounded edges and corners.Some also said the elevator buttonsreminded them of the iPhone's home button.Even the toilets seemed similar to the iPhone's square shapewith rounded corners, they added.The main structure of Apple's new headquarterswas built as a complete circle with glass walls on all sides.It rises up four levels from the ground.Apple's late chief Steve Jobs once described the future buildingas looking "like a spaceship landed."Jobs presented his plans for the project to local officials in June 2011,just months before his death.In the presentation, he outlined his plans to make a beautiful building inside and out.He noted that using curved glass all the way along the buildingwould be expensive and complex, but well worth the effort."There's not a straight piece of glass in the building," he said.The main building actually houses the world's largest piece of curved glass.Thousands of smaller pieces were used to make a continuous glass wallthat will stretch more than six kilometers.The property includes a 1,000-seat auditorium for meetings and product launches.Employees also get access to a large fitness center,as well as sitting areas and cafes to buy food.The entire property – also known as Apple Campus 2– was built to hold all the company's employees in the area – up to 14,000.The campus includes research and testing buildings.It also has an "Energy Center" to store the power Apple generates itself.The company says the property will be powered by 100 percent renewable energy.Architecture company Foster + Partners has overseen the project.It called the building "one of the most environmentally sustainable projects" in the world.The area inside and all around the building will be landscaped like a park,with more than 8,000 trees and plants.Steve Jobs said it was his goal to make 80 percent of the property green space.Much of the parking is hidden underground.There will also be running and biking pathsand hundreds of bikes available for employee use.Apple's goal of engineering and design perfectionseemed to be very much alive throughout construction.One union official said every detail – no matter how small– always required approvals from Apple managers.The official told Reuters that all materials and operations were checked and recheckedby Apple's in-house team and construction contractors.Workers often wore gloves to protect the more delicate parts of Apple's new spaceship."It's like a painting that you don't want to touch," the official said."It's definitely going to be something to see, if they let you in."