"built over" in the following sentence

Hello,

I am editing a translation where my interpretation of a particular sentence differs from that of the translator. Here it is:

On a crowded planet, the sort of places where a whole society can be culturally self-sufficient are hard to reach; Utopia was built over long ago. (From Arabs by Tim Mackintosh-Smith, p. 15)

The translation of the second part (translated back into English) reads more or less like this: "this utopia is now far back in the past".

I interpret that part as "Utopia was built over [with other structures] long ago [and is no longer visible/in use/functioning/inhabited etc."

Both interpretations are arguably close but I take the capital U in Utopia to allude specifically to Thomas More's Utopia and not any old utopia.

I would greatly appreciate a native speaker's input on this.

Thank you very much in advance.

Yours,

Ali Suat Ürgüplü