First you have to defeat the Executive in the Radio Tower at the 5th Floor. He will then give you a basement key. Leave that building and go into the short house next to the man who rates names. If you havent already defeated the people there, you will face about 5. Once defeated you will notice a passage way to the right. Face the door and press A and your in the basement. :D
you get the card key for the radio tower in goldenrod by saving the director from the underground basement. Talk to him and he should give it to you.
In Pokémon Gold, Silver, and Crystal, the key for the Goldenrod City Underground is found in the Goldenrod Department Store. You need to go to the store's basement, where you will encounter Team Rocket. Defeating the Team Rocket members will allow you to obtain the key, which you then use to access the underground area.
use the basement key in goldenrod city. the key is in goldenrod.
goldenrod city
I think that you find it somewhere in Goldenrod City Underground, after that you can save the Director. All you need is a Basement Key for G/S/C.
In case in goldenrod city take the underground path. There will be a door. Get the key from the rocket executive in radio tower. In case of lavender town we can't go underground.
Team Rocket's hideout is in Mahogany town. Team rocket can be found in the radio tower and in the underground basement in Goldenrod after you beat Pryce of Mahogany town (who cannot be fought until you take down team rocket in the same town), but they have no "hideout" in Goldenrod.
The bf in the department store and in the underground hall thingy in goldenrod city
Hit switches 3, then 2, then 1.
In Goldenrod city and in the kanto region, outside of saffron city
Underground in Goldenrod City.
In the north of the city, west from the gym (next to the Name Rater's Tent)