Pokemon Tower

The Lavender Pokémon Tower located in Lavender Town was a place of dread in Generation 1, due to Bird Jesus, the strongest Pokémon, being unable to deal any damage on the Pokémon inside it. Despite this, Digrat's namesake attack proved incredibly useful because it not only hit Ghost types, but was super effective against the Gastly line, which was part poison.

It is also known as the place where Rick Gastly was caught.

FireRed
In FireRed, due being a randomizer, the Pokémon Tower was used as a grinding spot.

In Generations 2 and 4.5, it was converted into a radio tower, with all threats from within removed and access limited to the first floor.