On 1 May 2004, ten new countries joined the European Union. I like to group them as follows:
The Visegrád Four, named after a Hungarian town where an important early- 1990s agreement was signed: Czechia, Hungary, Poland and Slovakia.
The Baltic States: Estonia, Latvia, Lithuania.
Slovenia - the only Yugoslav successor state to join at that point.
Two Mediterranean Islands: Cyprus and Malta.
I happened to be in Slovakia in October-December 2008, just before that country joined the Euro currency.
In some sense, getting former parts of Austria-Hungary to join became a major project of Otto von Habsburg, last Crown Prince of that empire, toward the end of his life. He came to congratulate Slovakia that June at a meeting of the Pan-European Union in Banská Bystrica. From there, he left en route to Sarajevo for the 90th anniversary of the assassination of Archduke Franz Ferdinand. He was already 91 at that time and doubtless not counting on being there for the centennial. As it turns out he passed away in July 2011.
As it happens, my friend Alexander Daško, a primas, or violinist band leader, was providing entertainment for Habsburg's meeting. I write about this reincarnation of the old Empire as the EU in my book, Travels with Ferdinand, which recounts my travels around Otto's family's former realms for the centenary of WWI's outbreak. The book, a very timely look at aspects of European history and culture related to today's Ukraine conflict, may be purchased at the link below - just click on the image!