What was the point of the technodrome?

[Original TMNT Cartoon Fan]

Originally Posted by Mutagen

I mentioned the artillery but forgot to add - for those unfamiliar with the classic toon, Technodrome was also indestructible just like Technodrome II in Turtles Forever it had the same kind of force field

What was that moving fortress in "Turtles at the Earth's Core" called? It was also like the Technodrome.