Across Eastern Europe, an unusual project is taking shape. The Extreme Light Infrastructure (ELI) will be a flexible, multi-purpose facility, hosting a variety of light sources in different countries. Funded by the European Union to the tune of €700 million, and set to be operational in 2015, ELI will be a hub for fundamental and applied research — laser and particle-accelerator engineering, biology and medicine, X-ray and gamma-ray imaging — as well as a promoter of technology transfer. It's an ambitious task, but ELI promises to become a research leader in fields including laser acceleration, vacuum physics, attosecond science and photonuclear physics.

Three of the four planned ELI sites have already been chosen. The first, in Prague, Czech Republic, will host a compact laser–plasma accelerator, providing ultrashort beams of energetic particles (10 GeV) and radiation (up to a few MeV). At the second site in Szeged, Hungary, a femtosecond laser will take snapshots of attosecond-scale electron dynamics in atoms, molecules, plasmas and solids. Nuclear processes will be investigated using a 30 PW laser housed at the third site in Magurele, Romania.

The location of the fourth site — possibly adjacent to one of the existing sites, or even in another country — will be decided later this year. And this is the big one: this site will be home to the real star of the ELI programme, a 200 PW, ultraintense laser, which is expected to advance laser acceleration to the ultrarelativistic regime.

Hosting the state-of-the-art ELI light source is a prize valued more highly by Eastern European nations than it would be by any other EU state. Although it is more than 20 years since the fall of the Berlin Wall and of the 'iron curtain' that divided the continent, science in Eastern Europe is still struggling against insufficient funding, an outdated research infrastructure and the consequences of decades of 'brain drain'. EU grants and other attempts to promote the return to Eastern Europe of its scientists working abroad have done little to alleviate these problems.

Meanwhile, Eastern European scientists are finding better access to funding and research facilities through joining international collaborations. Eastern European countries are heavily involved both in projects at the DESY laboratory in Hamburg, Germany, and in the experiments running at the Large Hadron Collider at CERN, in Switzerland — Hungary, Bulgaria and the Czech and Slovak Republics having all become CERN member states in the 1990s, Romania currently a candidate for accession. The advantages of such collaborations are undeniable, although long periods working away from home may be less than desirable for the scientists.

ELI, however, will support the science communities of Eastern Europe by creating local opportunities. Moreover, it will bring large international collaborations into Eastern Europe. The fourth ELI site, hosting its highest-intensity light source, is expected to be ranked eventually among the world's leading laboratories — each of the candidate sites is no doubt conscious of the advantages that will confer. It will be a difficult decision, but ultimately one site must be chosen to shine.