Thanks for the link! So it's on the Forgotten Continent then? Asuming that the answer is connected to Terra.

I'm going to wager this: Ipsen's Castle. I do have another guess having to do with Terra but little reasoning to go with it, I will state it if this one is incorrect. The reasoning:

Once I was there, --> see the next line.
That was long ago. --> The story of Ipsen that Zidane tells to Dagger.
The first thing I will do --> see the next line.
Is find it yet a again. --> Not certain.

Wait lets explore, --> Not certain.
And strive to find. --> Not certain.
A soul, a stone, --> The Gnomes.
And a reflection of my home. --> Not certain.

It feels so close. --> Not certain.
But never quite the same. --> I don't know.

Also, the summoner village is named マダイン・サリ Madain Sari in Japan which means that it is named Madain Sari over here in the USA.