Possible Clues:

• City lost, in last resort accepting opponent
• Legendary island that sank beneath the sea
• Fabulous island finally ejects saint and isn't converted
• Books I found among maps showing continent
• Fabled lost realm
• Not, after disappearance of old, island seen in maps
• Book about knight and time on one idyllic island?
• Lost land last carved up without objector
• Legendary underwater city
• Legendary 23