When Minas Ithil the Moontower was built in the late Second Age, the craftsmen who constructed it used their arts to trap living moonlight within its walls, giving the entire city a shimmering silver glow. Long afterwards, the tower was captured by the Nazgûl and became Minas Morgul, the Tower of Sorcery. Its glow remained, but was corrupted to the Morgul-sheen, a sickly luminous green that suffused the tower and the vale in which it stood.