From the city of Thessalonica take the road towards Halkidiki. After approximately 60 km, at the intersection right after the village called Moudania take the exit towards Sithonia-Nikiti.
Nikiti is located roughly 40km after the exit. When you reach the main intersection of Nikiti turn right towards the sea. Once you reach the sea turn left and drive just about 2 km until you find our little paradise called Castri.
If you have a GPS you will have to put the direction with these coordinates 40.198036, 23.680762.