What is in the brightest area of the night sky? When I look up in the night sky, I assume the brightest area, commonly known as "The Milky Way", is the Galactic Center of our home galaxy. 



But then I stumbled upon this illustration, which seems to suggest what I'm seeing is (and by far) not the Galactic Center. In fact, from this picture it looks like the brightest area might be the closest spiral arm (on the opposite direction of the galactic center).



I know this illustration is not meant to be precise, so it's probably not the closest spiral arm either. 

So, what am I really looking at when I stare at the brightest spot of the night sky? What percentage of it would be stars, planets, and nebulae? And what's the farthest object I can see in that direction with my unaided eyes?
All quoted text in this answer is from image captions in the Wikipedia article on the Milky Way.


  360-degree panorama view of the Milky Way (an assembled mosaic of
  photographs) by ESO





  This magnificent 360-degree panoramic image, covering the entire
  southern and northern celestial sphere, reveals the cosmic landscape
  that surrounds our tiny blue planet. This gorgeous starscape serves as
  the first of three extremely high-resolution images featured in the
  GigaGalaxy Zoom project, launched by ESO within the framework of the
  International Year of Astronomy 2009 (IYA2009). The plane of our Milky
  Way Galaxy, which we see edge-on from our perspective on Earth, cuts a
  luminous swath across the image. The projection used in GigaGalaxy
  Zoom place the viewer in front of our Galaxy with the Galactic Plane
  running horizontally through the image — almost as if we were looking
  at the Milky Way from the outside. From this vantage point, the
  general components of our spiral galaxy come clearly into view,
  including its disc, marbled with both dark and glowing nebulae, which
  harbours bright, young stars, as well as the Galaxy’s central bulge
  and its satellite galaxies. As filming extended over several months,
  objects from the Solar System came and went through the star fields,
  with bright planets such as Venus and Jupiter. For copyright reasons,
  we cannot provide here the full 800-million-pixel original image,
  which can be requested from Serge Brunier. The high resolution image
  provided here contains 18 million pixels.





  Here is a schematic map of our POV in the Milky Way galaxy.
  
  Observed (normal lines) and extrapolated (dotted lines) structure of
  the spiral arms. The gray lines radiating from the Sun's position
  (upper center) list the three-letter abbreviations of the
  corresponding constellations.





  A "God's view" map of Milky Way as seen from far Galactic North (in
  Coma Berenices). The star-like lines center in a yellow dot
  representing the position of Sun. The spokes of that "star" are marked
  with constellation abbreviations, "Cas" for "Cassiopeia", etc. The
  spiral arms are colored differently in order to highlight what
  structure belongs to which arm. H II regions are marked as dots
  colored in the same color as their spiral arm. They come in three
  sizes, measured by the excitation parameter U: small - U > 200 pc cm-2
  medium - 200 > U > 110 pc cm-2 large - 110 > U > 70 pc cm-2




It turns out we are in an arm -- the Orion-Cygnus Arm. The much brighter part of the Milky Way from our POV is in the direction of the galactic center, but the actual nucleus around the supermassive black hole is obscured by dust. If it was visible, it would be quite bright. What we are seeing that is bright is mostly the pseudobulge, or galactic bar formation, in the middle of the galaxy. We are looking at the galactic bar almost end-on, so it resembles a sphere from our POV.