ruins
墟 centers on the remains of something that once stood: ruins, wreckage, or a deserted site left behind after destruction or abandonment.
墟 combines 土 (earth, ground) with 虚, which likely contributes both sound and the idea of emptiness or hollowness, together suggesting an empty, ruined place on the earth.
The earth radical 土 beside 虚 (emptiness) paints a picture of an empty, abandoned patch of ground: a ruin.
For キョ, imagine a key (キョ) lying forgotten among the ruins, the last remnant of a door that no longer exists.