The Pennsylvania Convention Center is a multi-purpose complex that provides exhibition space as well as space for the historic Reading Terminal Market. The current main entrance, the Reading Terminal Headhouse, was once the Reading Railroad station and headquarters. The headhouse and single-span arched train shed, said to be the oldest in the world, were designed by Wilson Brothers Architecture & Engineering in 1891, elevated above the Reading Terminal Market. Currently the headhouse office space has been converted by the Marriott Hotel, the train shed converted into a convention center, and a new addition has been added to the north by Thompson, Ventulett, Stainback and Associates. In 2006, another $700,000,000 addition was approved to expand the facility to a total of 1 million square feet and 6 blocks. Model created by Matt Brown and Zach Moore.