If you're talking about Silph Co, its on the 4th floor on the bottom, a rocket grunt will drop the key after you defeat him in battle. He will be furthest south from where you are, hes behind a wall that wraps around the whole floor.
The card key is located on the 5th floor of the Silph Co. building in Saffron City.
on the fifth floor in the thick hallway
You find the red key card when you chase the thief on the scooter. You don't use it right away. The key card opens the door to the Black Widow's art room, where you complete the game. (You need the key from the curator of the Museum to track her down.)
To get the card key in Pokémon Fire Red you need to go the 5th floor in the Silph Company. You will find the card key after defeating the Team Rocket members.
you open a lift with it
The red card dropped by the Black Widow is a key card that opens the vault in her underground lair. If you return to the museum after picking up the card, you will receive a package that takes you to another island, to enable you to find the missing painting.
You get the key card from inside the Silph Co. and head to the 5th floor via the elevator.
Where to FIND the key card in Pokemon platinum was your question right ? well I looked for it on my game but couldn't find it. I think you mean galatic card,secret key. Secert key: location wifi galatic key; get it in building when battling someone
you don't, dummy.
The Card Key is located on the Fifth floor in Silph Co. Clear at the bottom by a Rocket Grunt.
Once you get the card you see the black widow on it and go to that house and go inside with the key and you will find the the painting and click on it then once you find the door use the card.
The card key is located on the 5th floor of Silph Co in Saffron City.