London - Seasoned Greek international defender Sokratis Papastathopoulos became Arsenal manager Unai Emery's third signing in the close season on Monday, putting pen to paper on a long-term contract for an undisclosed fee.
The 30-year-old, capped 79 times, will be reunited with former Borussia Dortmund teammates, Armenian playmaker Henrikh Mkhitaryan and Gabonese striker Pierre-Emerick Aubameyang.
"Greek international Sokratis Papastathopoulos has joined us on a long-term contract for an undisclosed fee," the club said in a statement on its website.
The defender arrives from Borussia Dortmund, where he won two Bundesliga titles and one German Cup, and has previous experience with Werder Bremen, AC Milan, Genoa and AEK Athens.
Sokratis joins Swiss veteran full-back Stephan Lichtsteiner and German goalkeeper Bernd Leno in linking up with the Gunners ahead of the new season.
His international career stretches back to 2008 and includes appearances at the Euro 2012 championships - he was sent off against Poland - and at the 2014 World Cup, scoring in the last 16 clash with Costa Rica, although the latter ultimately went through on penalties.