Where in the Superman comic books is the city of Kandor located?

Among the known points of interest on Krypton was Kandor, Krypton's capital city and its center for scientific research and study. It was in Kandor that the elders of Krypton met. Kryptonopolis was the planet's secondary capital. One of the planet's most spectacular sights was Mt. Mudru, which at 211,000 feet above sea level, was Krypton's highest point. Other sights were the Ruins of Xan, home of the civilization of the Kryptonian's ancestors, and the Glass Forest, a huge glen that was crystallized into glass by the heat from a powerful explosion.

A good clue: Something happened to its "location" (bit cryptic but thats all you are getting)
Come to think of it it could be a "Double" answer?

Hummm. I am not sure someone come and help me here!

Was Kandor the miniature city under a glass dome in the Fortress of Solitutde?

Kandor was located in the "Fortress of Solitude" ,then, when destroyed, "The Phantom Zone", and then again in the Fortress when restored.

http://www.supermanhomepage.com/comics/who/kandor.html

I give up Bedstor! Answer please?

I recall it as being a miniaturised city in a glass bottle ...

..apparently in Action Comics, June 1958.