Daystrom Station is a secret Starfleet facility storing experimental weapons and alien contraband, from which the Changelings stole Picard's original body.
Daystrom Station is a heavily guarded Starfleet installation that holds experimental weapons, alien artifacts and confiscated technology. The portal technology used by Vadic's Shrike was stolen from it, and the Changelings also took Picard's original body, which had been kept there after his mind was moved into a synthetic body.
In The Bounty, Worf, Raffi and Riker infiltrate the station using Krinn's device. They find a synthetic body built by Altan Inigo Soong that holds the memories of Data, Lore, Lal and B-4, and recover it before Starfleet arrives.