Short answers, pulled from the story.
The first Solvay Conference took place on the 30th of October 1911 inside the Hotel Metropole in Brussels. Ernest Solvay personally invited thirty scientists to attend this initial gathering.
Hendrik Lorentz served as chairman for the first conference while Albert Einstein and Niels Bohr led arguments during the fifth conference. Werner Heisenberg stated that the exchange at this meeting contributed extraordinarily to the clarification of physical foundations.
Albert Einstein declined his invitation because he protested against the exclusion of German scientists following World War I tensions. Anti-Semitism was rising at the time so Einstein accepted an invitation from Dr Chaim Weizmann for a trip to the United States instead.
Marie Skłodowska-Curie won Nobel Prizes in two separate scientific disciplines among all attendees. H. A. Lorentz received his award in 1902 while P Zeeman also won that same year and Albert Einstein won his award in 1921.
The archives from 1910 to 1962 are kept at the Free University of Brussels and ESPCI Paris. UNESCO added these archives to its Memory of the World International Register during 2023.