[Kransha]

Here's a curious...ummm...flaw, relating to the building of Lugburz.

In The Tale of Years, Second Age, it is stated:

-1000 Sauron ... chooses Mordor as a land to make into a stronghold. He begins the building of Barad-dur.

-1600 Sauron forges the One Ring in Orodruin. He completes the Barad-dur. Celebrimbor perceives the designs of Sauron.

Now, that's fine, except for one thing.
In FotR, Elrond states very clearly and firmly:

"The Dark Tower was broken, but its foundations were not removed; for they were made with the power of the Ring."

Ok, something's wrong here. The One was forged in 1600 of the Second Age. How could Sauron have been building Barad-dur for 600 years without any foundation. So, he built the whole tower like a log on the ground, then put up the foundation instantly with the ring forging in 1600 and put up the Dark Tower over it like some crazy giant architect? That could be some metaphor for ring power, but Elrond is being awfully specific.