Related Clues:

• Right-angle pipes
• Lawful ends?
• 90-degree extensions
• Extensions on some buildings
• Letter-shaped extensions
• Some angled building extensions
• Elongated 90-degree shapes
• New wings, often
• The black square chunk in front of 55-, 60- and 63-Across, and others
• Some wings or joints
• Compound formerly known as 'white vitriol'
• Some building annexes
• The two of "Hello!"
• Some building add-ons
• They follow K's