http://confluence.org/confluence.php?visitid=14714 : "according to the research of the French National Geographic Institute, the one and only geographical central point of the continent is in Lithuania, a fact that even won recognition in the Guinness Book of World Records"
crwflags.com
http://www.crwflags.com/fotw/flags/pl-pd-sw.html : "In 1775 royal astronomer Szymon Antoni Sobiekrajski published a report in which he stated that Suchowola is the exact geographic centre of Europe"