Kaliningrad is a Russian territory between Poland and Lithuania, which are surrounded by EU territory after the EU enlargement in 2004.
At the EU Summit in Brussels in October 2002, the EU agreed upon a special visa system for this enclave, a Facilitated Railway Transit Document - as well a simplified visa scheme for Russian citizens travelling between the Kaliningrad region and the rest of Russia.
Links
http://assembly.coe.int/Docume......WorkingDocs/doc02/EDOC9570.htm