Ecruteak City is a city in the Johto region and the location of the forth Gym. The Gym Leader of this city is Morty who specializes in Ghost-type Pokémon and hands out the Fog Badge if the player defeats him.
The Burned Tower used to be as tall as the Bell Tower before it burned down in a mysterious fire 150 years prior to the events of Pokémon Gold, Silver, Crystal and their remakes. Lugia also used to live here, moving to Whirl Islands when the tower burned down. The legendary beasts: Raikou, Entei and Suicune can be encountered for the first time in the basement, after which they flee.
It is also the place where Silver will challenge the player for the 3rd time.
A house that you cannot enter in Olivine City features an NPC that speaks of a pharmacist in Ecruteak City who had treated her Pokémon, despite the pharmacy being in Cianwood City instead. This is either a mistranslation, or a hint of the pharmacy originally being in Ecruteak City in the Beta version of Pokémon Gold and Silver. Evidence of the latter is that there's another inaccessible house in Ecruteak City, near the Mart and PokéCenter.