As is known, it's impossible to see a Sun lamp in Blender rendered scene (Cycles render engine). We can light objects in a scene with sunlight, receive bouncing light, shadows, caustics, et cetera..
But we can't rotate/navigate the scene so that to see the Sun "as is".
This is the principle of this light source: the sun emit light but doesn't visible..
But there is an interesting trick: we can behold the sun reflection!
If we create any specular surface and rotate it to catch correct angle for the reflection, we will «see» the Sun!
There is one difficulty: the Sun lamp settings.
The Sun size doesn't measure in «Blender units», it is more correctly consider this units as Sun angular size, where 1 unit is approximately equals ∏/1000.
Prompt, ∏ — 3.14 rad or 180°.
In this video I experience different Sun lamp settings: size, strength, color.
As you can see, have too big Sun is to be impossible to see it as a whole object. The optimal Sun size (for our goal in our scene) is 0.100, pay attention.
To see a Sun lamp in Blender (Cycles):
Sun lamp position and settings: