On the western outskirts of Thessaloniki, behind the main railway workshops, several hundred railway carriages and locomotives have been sitting in open sidings since being decommissioned across the 20th century. Some date back to the Ottoman period; others are postwar Greek and Yugoslav rolling stock. They rust in the open air, overgrown with vegetation, some completely cannibalized for parts, others nearly intact.
This is not an official attraction and the site is technically railway property, but it is accessible and photographers and urban explorers have been visiting it for years. The scale is genuinely surprising — you don't expect a train graveyard this large on the edge of a major city. Take a taxi to the Thessaloniki railway workshops area and walk in from the road. Don't go alone and don't go after dark.