Related Clues:

• European airline
• See 1-Across
• 'The final frontier'
• Margin
• Locale of the Cantabrian Mountains
• Theme of this puzzle
• Opening
• Part of NASA
• Where the Tagus flows
• 1982 Michener epic
• Panhandle site
• Spain and Portugal
• Albéniz piano masterpiece
• 7.2 million-dollar bargain
• Berth