The former AC Milan defender has signed a contract until 2018 for a reported fee of around €9.5million but the finer details of the agreement have been left disclosed for now with more to be revealed later.
The Greece international believes that his career has benefited largely due to his time in Italy where he spent two spells at Genoa and in-between made 5 appearances for AC Milan.
Dortmund bought the centre-back presumably to replace Felipe Santana who has recently swapped clubs to try his luck out at Schalke 04.