L. Sprague deCamp

The Glory that was - or the Glory that wasn't? Knut Bulnes had considered Vasil IX, World Emperor of the 27th century, to be a harmless eccentric until Imperial decree completely sealed off Greece behind a force wall and people of Greek descent suddenly began disappearing from the rest of the world - including the wife of Bulnes's friend Wiyem Flin. Bulnes reluctantly agreed to help Flin find his wife, and the two managed to get inside the force wall only to find themselves in the Classical Greece of Socrates and Euripides - and the target of a man-hunt not only by the soldiers of Perikles, but also by the unpleasant characters with machine guns.

Books like The Glory That Was

Your next favorite book is out there