The construction of the Burj Khalifa was a massive human undertaking that required a peak workforce of approximately 12,000 workers on-site every day. Over the course of the six-year project (2004–2010), these workers—hailing from more than 100 different countries—contributed a staggering 22 million man-hours to complete the 828-meter tall structure. The workforce was highly specialized; while thousands were involved in the high-speed concrete pumping (which set a world record for height), others were dedicated solely to the installation of the 26,000 hand-cut glass panels that make up the exterior cladding. At the height of construction, the tower was rising at a rate of about one floor every three days. The logistics were equally impressive, with a dedicated fleet of high-speed hoists moving thousands of workers up and down the structure daily. This immense labor force worked around the clock in shifts to overcome the extreme desert heat and the unprecedented engineering challenges of building the world's tallest skyscraper, ultimately finishing the spire that can be seen from nearly 95 kilometers away.