Alfred Einstein became a regular visitor to Brussels, participating in the Solvay Congresses established in the Belgian capital by the industrialist Ernest Solvay. A famous picture of the first of these events, in 1911 at the Hotel Metropole, shows 24 of the most eminent physicists and mathematicians of the day, including Einstein. Of these, 23 are men. One woman takes her place in this exalted company, the remarkable Marie Sklodowska-Curie.