"The founding of this university took place in 1723" - "La fondo (or: la fondado) de tiu ĉi universitato estis en la jaro 1723".
It's the action seen as a noun. Basically saying that the university was founded in 1723.
The foundation of a house is "fundamento (de la domo)".
So "la Fundamento" (the basic documents describing authoritatively what Esperanto is) is basically the foundation of the language.