Saturday's peaceful rally began in Heroes Square - the heart of the Hungarian capital.

BBC: Thousands of Hungarians rally to back embattled PM Orban

But by the time they set foot on Australian soil, Gyarmati and his teammates were informed of a brutal turn of events as Soviet forces ruthlessly reasserted their grip on the Hungarian capital.

CNN: March 2, 2012 -- Updated 1645 GMT (0045 HKT)

The World Science Forum follows in the footsteps of the World Science Conference organized in Budapest in 1999 by UNESCO and ICSU. Unlike the previous sessions that were held in the Hungarian capital in 2003, 2005, 2007, and 2008, the next Forum will take place in Rio de Janeiro (Brazil).

UNESCO: Budapest World Science Forum to examine the changing landscape of science | United Nations Educational, Scientific and Cultural Organization