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 27th 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).