A study has crowned Real Madrid as the best club between 1901 and 2001...
The Spanish giants finished out in front of Juventus, who were second, while Barcelona, Milan and Bayern Munich completed the top five in the historic record books.
In recent seasons the IFFHS have judged clubs in order of merit, but have only done so in the Club World Ranking that began in 1991.
Demand was high for a ranking based on titles won, placings in competitions and other factors over the entire 20th century, and now the IFFHS have explained how they reached their conclusion.
"For some years now, the IFFHS has been asked by clubs, sports journalists and fans to determine the clubs of the century for the individual continents but on a realistic basis without imaginary values and subjective influences," the statement on the IFFHS website explains.
"The rankings published so far have been based on the number of titles won or placings or marathon tables in competitions.
"Because the Club World Ranking (by IFFHS) has been determined monthly only since January 1991, it cannot be used as the basis for determining the club of the century.
"The IFFHS has decided these continental clubs of the century and with it continental rankings of century to determine exclusively on the base of individual match results of the continental club competitions.
"The national competitions are merely a prerequisite to qualify for the continental club competitions. Intercontinental club competitions were not taken into consideration."
A point system saw clubs rewarded for their performances in the Champions League, UEFA Cup, European Cup Winners' Cup, Mitropa Cup, Copa Latina and the European Super Cup.
Below are the top ten clubs of the 20th century:
563.50 Real Madrid
458.00 FC Barcelona
399.75 AC Milan
399.00 Bayern Munich
Lucas Brown, Goal.com