Hi there, I was doing some work on cycles for my CG class and even though I used this absurd amount of samples the image is still full of dots.
Am I doing something wrong? I am kinda new to CG and blender, thanks for any help 
7000 samples 1600x900
Is the lamp is the only mesh emitter and light you have? then this is probably partly the issue, cycles mesh emitters are poor when they are small in size. for a night scene this is difficult to do, although I would suggest you would require some ambient light, maybe from the background colour, or sky texture node. You could also have a sunlight to emulate the moons light at a small value with a hint of blue - if you want sharper less diffused shadows, make the sun (in properties) a lot smaller.
Also I think you have glass for the lamp around the top - there is what appears to be IOR distrotion. The glass shader is very slow. If you really want glass, try using a mix shader with Transparent and glossy for flat objects like this - the only thing you’ll loose is the IOR, but that shouldn’t matter.
Generally Cycles isn’t real-world accurate, but then again neither is your scene, all outdoor scenes have ambient light emitting from one place or another.
Hope that helps 
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Thanks for the reply, I will try to do what you suggest this weekend. After it is done I will post another render.
Simplify the shot. Get the light up and the contrast increased. Make the problem easier, so to speak, for the computer to solve.
Then, post-process the finished shot to reduce its saturation and brightness. Just like shooting a movie “nighttime” scene in midday. The output of the renderer does not have to be “the perfect, finished, final output,” and it is often most practical when it isn’t.
If you start feeling like you have to add more iterations and not much is changing, it probably won’t change significantly even if you double or triple the number of iterations. If the shot is full of “speckles” but otherwise okay, you can “de-speckle” the thing in post.
Good tips in this thread. Here are some more.
Dont use the glass shader for pane glass, use a mix of transparent & glossy. Then disable caustics in the render settings (unless you really need it which you obviously don’t in this particular scene). This will remove some noise.
Also, there’s always some ambient light in a dark scene, even a night sky in the city emit some bounce light from light on the ground lighting up the sky from underneath. Try a small amount of AO for that. This will also remove some noise.
How can I achieve the distorsion of refraction with a mix between transparent and glossy?
I did what you guys suggested and it helped. I created more emission objects, a moon, used “no caustic” option, changed glass for transparent/glossy and changed the light values to make the scene brighter for now.
At first, it was very similar to the first image I posted, but with a lot less samples: 500 instead of 7000. Then I changed the world settings to sample as lamp and it improved a lot. This is the result now (500 samples). I hope that with a bit more iterations I can get rid of the noise on the wall… the only problem is the roof, it doesn’t seem to be improving at all.
Maybe is because most of the lights I created so far don’t reach it? Will try to create a very soft light on top of it to see if it helps and don’t affect the rest of the scene so much.
Again, thanks a lot for all the help!
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Now, if you want to give the feeling of the night, low the exposure parameter of the film in the omonimous panel.