MareNostrum is a large-scale supercomputer located in Barcelona, Spain. It was developed by Bull and is housed in the Barcelona Supercomputing Center. MareNostrum is known for its high performance and is used for various scientific research projects, including climate modeling, biomedical research, and simulations in physics. The supercomputer has undergone several upgrades since its initial launch in 2004, with the latest version, MareNostrum 4, introduced in 2017. It features thousands of processors and can perform quadrillions of calculations per second, making it one of the most powerful supercomputers in Europe.