User blog comment:Zippertrain85/Dawnguard Follow up./@comment-13446185-20131025003722/@comment-12599067-20131027003235

Sorry, but did Talos invade Black Marsh? I severely doubt he did. Therefore you can rule as Emperor without controlling all of Skyrim.

Actually, no, Serana's chamber is not the only place with such architecture. Many of the gates and other chambers show some form of similar architecture. The Forebears also use this architecture, as shown for their hideout in Haafingar.

No, Solitude was around them. According to Viarmo, one of the greatest scholars in Skyrim, it was indeed there.

If he killed them in secret, which he could have, no one would know. They would notice, but they can't do much, since he's a powerful warlord/king.