Some Story I Read Yesterday

Picture unrelated.
   I read an old sci-fi short story yesterday called "Nightwings" by Robert Silverberg, published in 1968. You don't know this about me, but I'm a science-fiction lover. Larry Niven is one of my favorite authors but my absolute favorite would have to be John Varley, who in one story wrote about a sentient black hole and the two women who hunted it. The thing was, the black hole only spoke to one of the two women, and let her know that the other one was planning to kill her on their return to civilization. That's some good stuff right there!
  But back to "Nightwings", this story takes place in the so-called Third Cycle of Earth, in other words the third age. The First Cycle would be our present age, the second was a time of high technology and a bit of magic, and finally the Third Cycle, where civilization is in decline and Earth has become a popular tourist destination for aliens across the galaxy. In this age, everyone is a member of a guild, or else is one of the guildless who are at the bottom of the totem pole so to speak. The story is written from the point of view of a Watcher, whose guild carries a cart of instruments around with them to Watch for a long-prophesied invasion of Earth. Four times a day a Watcher watches, scanning the surrounding galaxy for a hint of approaching warships. The Watcher is an old man in the story, and after Watching for so long and finding nothing is naturally starting to doubt if there really is an invasion. The guild of Watchers isn't looked very highly upon, and many people deem Watchers unnecessary.
  The Watcher travels with two companions, a female Flier named Avluela and a Changeling called Gormon. Fliers are members of the Fliers guild, but Changelings are all guildless. The only group lower in society than the Changelings in the story are the neuters, so Gormon's proud attitude and his intelligence are unusual for his species. Changelings are basically tall, muscular humanoids with different colored skin and eyes, but some are more unusually shaped, hence the name. Fliers have wings and can fly, but only at night, so that's from where the title of the story comes. Now, the three travelers are heading to a city called Roum, which you will recognize from the opening line, "Roum is a city build on seven hills." Other cities mentioned in the story are Perris and Jorslem. I like these kind of things in futuristic stories, I can't help it.
  The story deals with the three travelers' adventure in that ancient city, and with the Watcher who finally detects something in his Watching, or at least he thinks he might have. I won't spoil anything, in case some nutbread decides to look the story up and read it themselves. It's only about 50 pages long and I give it my recommendation, or else I wouldn't have bothered to write this long, poorly-made post. I would call it more a fantasy story than science fiction anyway, if that helps make up anybody's mind.