Heaven's Gate

Heaven's Gate (天国門 (ヘヴンズ·ゲート), Hevunzu Gēto) was a chaotic are of space in.

Overview
Heaven's Gate, along with its counterpart, Hell's Gate, appeared ten years before the start of the series. It's appearance sparked a large war five years before the start of the series, which resulted with the Gate, and everything within a 1,500 kilometer (932 mile) radius, vanishing. The area where the gate was has become inaccessible.

Interestingly enough, Heaven's Gate and Hell's Gate are located on opposite ends of the planet, however, it is revealed later in the anime that, despite the Gate's apparent disappearance, Dr. Schroeder, a scientist studying the Gates, believes that, due to no person being able to enter the area where the gate formerly was, combined with Lancelnopt synchrotron radiation still being detected there, the Gate still exists in some form that is invisible and intangible.