Justice League Watchtower are the secret headquarters of the Justice League of America, featured in JLA/Witchblade.
Sara Pezzini was brought to the Watchtower after she stumbles into Oracle's apartment. There she was examined by the Justice League as the Witchblade forms a protective cacoon around Sara in order to heal her wounds. Later the Huntress is possessed by a fragment of the Witchblade and is brought to the Watchtower for examination. After Sara recovers from her wounds, the Justice League finds out that Wonder Woman is now possessed by the Witchblade and proceed to go after her.