Employees are facing an unusual problem at the new Apple headquarters in Cupertino, California.

One of the defining features of the office, located on the stunning 175-acre campus, is the abundant use of glass panes. Unfortunately, they have been rather hard to spot as employees have been walking right into them.

According to a new report from Bloomberg, the staff had tried to navigate around the problem by sticking Post-It notes on the glass surfaces. But they were soon removed in order to preserve the aesthetic design of the office.

The building is surrounded by 45-foot tall curved panels of safety glass. The interior work spaces, known as "pods", are also made of glass.

The office was designed by Apple design chief Jony Ive and British architectural firm Foster + Partners. After the unveiling of the first look, the campus architecture was praised by fans and publications for its sleek appearance. The futuristic design, which includes a circumference almost a mile long, resembles a circular spaceship which earned the campus its nickname.

"While it is a technical marvel to make glass at this scale, that's not the achievement," Ive said in an interview with Wired Magazine. "The achievement is to make a building where so many people can connect and collaborate and walk and talk."

A 30-acre courtyard is located in the middle of the ring-shaped building which consists of a pond, fruit trees, and winding pathways.

"The workspaces and parklands are designed to inspire our team as well as benefit the environment," said Apple CEO Tim Cook last year. The campus runs on renewable energy using solar panels from the main building.

With the size and facility to house nearly 13,000 employees, the £3.5bn ($4.9bn) Apple Park was originally proposed by Steve Jobs shortly before his death in 2011. The employee move in was initially projected to take place in 2015, but eventually happened in April 2017.