Voldemprt's Lair is a location visited in Chapter Fourteen of My Immortal. It is a lair belonging to Voldemort.
Vampire Potter transports himself and Enoby there by use of a spell. When they arrive, they hear Voldemort cast "Allah Kedavra!" Only, it's not Voldemort, it's Snaketail, torturing Draco. Snaketail falls in love with Ebony, but she rejects him, stabbing him in the heart with a gun. The goffs hearing Voldemort's high heels clacking, and use their never-before-seen broomsticks to escape.
Voldemprt's Lair is never described, and it is thus unclear what it looks like.