At the heart of downtown Manhattan, where the original nine-story 4 World Trade Center originally stood, is now the 72 story, 977-foot-tall World Trade Center Tower 4. Home to commercial and retail occupants, the skyscraper encompasses 2.5 million square feet of space. WDF draftsmen completed the project’s piping drawings, while HVAC crews installed the tower’s piping and mechanical equipment including sleeves and inserts, risers, and packaged AC units to supply the building with heating and air conditioning.