The cool, dry and cloud-free Atacama Desert in Chile offers ideal conditions for astronomical observations and is already home to several telescopes. It is therefore not surprising that the world's largest telescope is also being built there, on the 3,046-metre-high Cerro Armazones mountain, and is expected to go into operation in 2028. With the help of the ELT, scientists hope to gain new insights into the early history and future of our universe or even discover new, earth-like planets. PERI supplied the formwork and scaffolding systems required for the construction of the foundation as well as for the wall structures and the central base of the telescope.