There is no building known as "Mercury City Tower". It's possible you are thinking of a different building, or the name has been misremembered.

Could you please provide more information or context about the building you are referring to? For example:

* Location: Where is this tower located? (City, Country)

* Other details: Do you know anything else about this building, such as its purpose, developer, or approximate height?

With more information, I can help you find the correct building and its height.