I am looking for the 10 biggest European hospitals by number of bed. I can't find this data anywhere.
This page shows a ranking of hospitals by size: http://hospitals.webometrics.info/en/europe?sort=asc&order=Size though I have no idea how reliable it is.
This page shows the number of hospital beds per country: http://stats.oecd.org/index.aspx?DataSetCode=HEALTH_STAT# (under 'health care resources' -> 'hospital beds')
Some wikipedia pages (in native languages) seem to have the number of hospital beds per hospital, though this is not a complete picture: https://en.wikipedia.org/wiki/Lists_of_hospitals_in_Europe
Some wikipedia pages with hospital beds: