Kastro (Sifnos)
| Kastro Κάστρο | |
|---|---|
| Settlement | |
| Coordinates: 36°58′28″N 24°44′43″E / 36.97444°N 24.74528°E | |
| Country | Greece | 
| Administrative region | South Aegean | 
| Regional unit | Milos | 
| Municipality | Sifnos | 
| Community | Apollonia | 
| Elevation | 80 m (260 ft) | 
| Population  (2021) | |
|  • Total | 124 | 
| Time zone | UTC+2 (EET) | 
| • Summer (DST) | UTC+3 (EEST) | 
Kastro (Greek: Κάστρο) is a settlement in Sifnos, Cyclades, Greece. According to the 2021 Greek census it had 124 inhabitants. Kastro is built on top of a steep hill near the eastern coast of the island, at an altitude of 80 meters. Below the hill there is a small bay, which was used as the port of the settlement.