Akihabara Radio Kaikan

Akihabara Radio Kaikan, often shortened to simply RadiKan, is a building in Akihabara, and is a key location in both Steins;Gate and Steins;Gate 0.

Steins;Gate
Radio Kaikan acts as the starting point for the story. It is where Okabe and Mayuri attend Dr. Nakabachi's conference and Okabe first meets Kurisu. It is also the location of Kurisu's eventual death on the Beta Attractor Field.

On the Alpha Attractor Field, a satellite crashes into the building, destroying the room Dr. Nakabachi was going to speak in. This event causes Nakabachi to cancel the entire press conference and the police soon close the building and surrounding area to the public. Later on, Suzuha in the anime takes Okabe and Kurisu to the building (this takes place in the Future Gadget Lab in the visual novel) and explains that the satellite is actually her time machine. Suzuha had attempted to land on the building's rooftop, but a miscalculation lead her to crashing the time machine into the side of the building. Okabe, Kurisu, Mayuri, Itaru and Suzuha then gather there to help repair the machine over the next several days. Suzuha eventually leaves, leaving an empty hole in the building for the rest of the story on this Attractor Field.

Back on the Beta Attractor Field, on August 21st, Suzuha lands successfully on the building's rooftop and calls Okabe there.

Steins;Gate 0
The final confrontation between Stratfo, DURPA, and Russian intelligence takes place on the roof and the disappearance of the time machine on top of the building is one of the convergence points that leads to World War III.