(WHTM) -- Malls are becoming less and less prominent in the United States. But there is one Pennsylvania mall that is thriving and is one currently of the largest malls in the country.

The King of Prussia Mall is located in King of Prussia, just outside the limits of Philadelphia. The mall itself opened on Nov. 25, 1963, and now is considered to be the third largest shopping mall in the country when it comes to top leasable space.

The mall opened in 1963 and was only one building. Called the Plaza, this was an open-air shopping mall which was anchored by J.C. Penney. According to thekingofprussiamall.com, in 1965 when Gimbels opened their store, The Plaza building became the largest shopping center in the East.

The Gimbels expansion required an enclosed section of the mall to be built on the north side of the Plaza Building.

In the mid to late 1970s, it was decided to start construction on a vacant 30-acre part of land next to the Plaza building. This would later become the second building, which was named The Court.

The Court at King of Prussia opened on Aug. 6, 1981, and was a fully enclosed shopping area that featured three department stores and 130 shops. Combined with The Plaza, the complex featured seven department stores and 250 shops and eateries. The complex as a whole occupied 2.4 million square feet of space and a covered walkway would connect both buildings.

Stores came and went from the mall throughout the 1980s and into the 1990s. In 1992, it was announced that the Plaza building would be completely rebuilt. Thekingofpruissamall.com states that management wanted to make the Plaza "more appealing to upscale retailers looking to capitalize upon the new demand for luxury goods."

The brand new Plaza building would open on Nov. 2, 1995, and made the mall the second largest in the United States, just behind Minnesota's Mall of America. After the new Plaza building was built, the mall featured nine department stores - which was the most in any mall in America during that time.

Fast forward to 2011, when it was announced that Simon Property Group would own 96% of the mall and would be linking both the Plaza and Court buildings together. This 140,000-square-foot expansion would link both buildings for the first time since the mall opened in 1963.

Construction on the connector began in 2014 and it opened in August of 2016. This connector added 50 new retailers and a brand-new parking garage.

Presently, the mall features over 450 stores, 30 restaurants, and features 2,293,200 square feet of retail space. According to Visit Philly, the mall attracts 22 million visitors a year and is still Pennsylvania's largest shopping mall.