Lower part of Wayne Manor

• Secret headquarters for Bruce Wayne
• It's under Wayne Manor
• Subterranean headquarters of a DC Comics superhero
• Comic-book hero's hideaway
• It lies beneath Wayne Manor
• Secret DC headquarters
• Part of Wayne's world
• Grotto under Wayne Manor, and an apt title for this puzzle

Wikipedia Word definitions in Wikipedia
The Batcave is the secret headquarters , command center and safe house of the DC Comics superhero Batman , the alternate identity of playboy Bruce Wayne , consisting of a series of subterranean caves beneath his residence, Wayne Manor .