1. * In the European city of Brussels, for the first time in its 52-year history, this world org. invoked its mutual defense charter known as Article V (which states that if one of its members is under attack, all other member nations will come to its defense) in response to the attacks on the United States, on the dark day that will forever be remembered in history ...September 11th, 2001
5. Aimlessly wander
9. * Leader in #27A (See #54A for a Related Clue)
13. Building extensions
14. Increased
16. * Norse deity
17. Turn Off, without the "R"
18. * River in France
19. Permits
20. * Certain Europeans
22. * Budapest is its capital
24. Ventilates
26. * It's in Europe: Isle of ___
27. * City Completer
31. * Capital of Wales
35. * Dutch cheese (pl.)
36. TV show taping devices
37. Thai language
38. Connective Tissue, minus the "ment"
39. * Sea between Europe and Asia
41. Antlered Animals
42. * Unit of money in Romania
43. * God of War, in ancient Greek Mythology
44. Arches
45. * Mountainous country that is a popular tourist destination
47. * Small republic located in the Pyrenees Mountains on the French-Spanish border
49. "The Addams Family" (TV) character
50. Horse's foot
51. * Birthplace of Napoleon Bonaparte
54. * Catholic Completer
58. Spongelike cake
59. * Part of the title of a play by England's legendary writer, William Shakespeare
61. * God of ancient Greece
63. * City in France (var. sp.)
64. * District in the Azores of Portugal
65. * Ireland's other name
66. Lost
67. Stringed Toy ...flipped around?
68. Not wild