Huge triangle passes over oblivious, sleeping capital

I was staying at my girlfriend's parents' home (They made us sleep in separate rooms) and I was awakened by a low-pitched, rumbling vibration and sound. I went to the window and opened it to look out. Almost my entire veiw of the sky was blotted out by a huge triangular shape with lights running down the sides and marking the corners. It seemed incredibly low and was moving very slowly toward the West. I watched until the entire length passed overhead and the rumbling began to grow more distant. I was astounded and wondered what to do--then I remembered that I was in the middle of a city and realized that this would be big news in the morning--it couldn't have gone unnoticed--so I decided to go back to bed! No one else that I know of saw a thing, so I've kept it largely to myself until now. The report from Louisburg NC seems to be very similar and may have been the same night. But mine made noise.
Date is approximate.  PD