I had a glorious mistake about a month ago. I play a lot at a local game store on a LAN. Every Sunday night, we hold RoR tournaments - just a big ffa DM.
So we're playing this tournament. I get Persian (we're playing random). I rush the Minoan player next to me off his 'island'. I wall off the Choson guy. I kill off the Roman guy.
By this point the Choson, the Assyrian, and the Minoan player had allied against me, and I began to lose land. Three hours into the game I still controlled the Minoan and Roman islands, but I had lost almost my entire army, and the Choson had more than 100 triremes dominating the lake(it was Mediterranean).
I chose to build a wonder. I gathered my last military units into a compact mass on the Roman island, on top of a tall hill. I walled around with three courses of walls, and dozens of towers. I stationed elephants between the walls. I built a vast fleet in the nearby river. My catapults controlled the ground against anything the gold-starved Assyrians and Choson could throw at me. The last of my gold went into building around 30 armored elephants to make a simultaneous assualt on the Choson and Assyrian bases.
I began my wonder. Cries of despair and protest went up from around me. Their assaults were thrown back from my magnificent castle. Suddenly, it came to me that what the Persian wonder needed was a patio. I placed and deleted a wall section next to my wonder. The crushed stone looked wonderful. I began the patio contruction, and allied with my opponents, so they could look upon my mighty works and despair.
Then...um...I deleted the wonder.
I have learned a valuable lesson in deleting objects next to very expensive buildings. Oops.