With more than 5,700 publications and over 3,000 solved protein structures in the last ten years,

BESSY II is very successfully approaching its 25⁺th year of user operation. Firmly embedded in the international science landscape and the League of European Accelerator-based Photon Sources (LEAPS), BESSY II is Germany’s dedicated soft X-ray source, providing 40 instruments in user service (https://www.helmholtz-berlin.de/user/infrastructure-at-hzb/beamlines---stations/index_en.html). and receiving beamtime applications from 58 countries. BESSY II’s particular focus on materials and energy science is mirrored in the current up-grade BESSY II+, and its strategic focus on operando methods for energy materials research. BESSY II+ provides new and novel possibilities, combined in a holistic way (https://www.helmholtz-berlin.de/forschung/quellen/bessy-2-plus-upgrade_en.html):

• Dedicated, unique instrumentation and sample environments with a focus on operando experiments for the energy transition

• Modernized source and experimental infrastructure
• Deployment of digital methods, automation, data handling and remote access
• Combination of synchrotron and laboratory infrastructure
• Steps towards a sustainable facility

The strategic, holistic, and comprehensive BESSY II + approach integrates the light source in a larger context of local and on-site infrastructures to allow multi-modal investigations using additional and complementary techniques, laboratories and auxiliary methods. This paves the way to an integrated research campus in Berlin with the Photon Source as a lighthouse.

BESSY II will remain in operation until the seamless transition to its successor BESSY III, with BESSY II+ as a scientific and methodological bridge (“The future of BESSY” DOI:10.1080/08940886.2024.2312051).

BESSY III is designed as an indispensable 4^th generation discovery machine in the soft and tender X-ray regime for materials and energy research and many other topics in physics, chemistry, biology, environmental research, medicine and more (https://www.helmholtz-berlin.de/forschung/quellen/bessy3/index_en.html).