A Tutorial!
I did this icon and was quite pleased with the results, and so I created a little tutorial to create the effect. Hope you guys will find it useful.

This is the original image:

I cropped this particular area because I wanted a bit of empty sky to put some text on:

Duplicate this base. Set the duplicate layer to 'exclusion' blend. Fiddle with the opacity a bit to get what you want (I used 50% opacity)
NOTE: If you set the layer to 'pin light', you get a nice effect too. Try it.
I noticed that the building blended in too much with the background, and so I increased the contrast a bit.
The end result:

Create a new layer. Use this gradient:

(The gradient is in 'Special Effects'; the first one)
Set this gradient layer to 'exclusion' blend, opacity of around 30% to 40%. You should get something like this:

Next, I created a new layer and used a brush from Annika von Holdt's collection:

- but really, all you need is a texture brush that you like. Set this brush to an opacity you desire, and use the Erase tool to erase away the brush from the buildings, so that only the sky is affected. Now you will get:

Now, the border. I can't remember where I got this border brushset from, but it was probably from
crumblingblock. I'm sorry if I got it wrong, though.

Put this brush on a new layer, set opacity to 83% to soften the icon, and then you have:

Almost, almost done.
Now, create two text layers above the gradient layer:

'city of' text layer: font = Georgia
'sin' text layer': font = Laine Day. Text effects = drop shadow.
And there you go:

The one with 'pin light' duplicate layer:

Hope this was useful. =)

This is the original image:

I cropped this particular area because I wanted a bit of empty sky to put some text on:

Duplicate this base. Set the duplicate layer to 'exclusion' blend. Fiddle with the opacity a bit to get what you want (I used 50% opacity)
NOTE: If you set the layer to 'pin light', you get a nice effect too. Try it.
I noticed that the building blended in too much with the background, and so I increased the contrast a bit.
The end result:

Create a new layer. Use this gradient:

(The gradient is in 'Special Effects'; the first one)
Set this gradient layer to 'exclusion' blend, opacity of around 30% to 40%. You should get something like this:

Next, I created a new layer and used a brush from Annika von Holdt's collection:

- but really, all you need is a texture brush that you like. Set this brush to an opacity you desire, and use the Erase tool to erase away the brush from the buildings, so that only the sky is affected. Now you will get:

Now, the border. I can't remember where I got this border brushset from, but it was probably from
crumblingblock. I'm sorry if I got it wrong, though.
Put this brush on a new layer, set opacity to 83% to soften the icon, and then you have:

Almost, almost done.
Now, create two text layers above the gradient layer:

'city of' text layer: font = Georgia
'sin' text layer': font = Laine Day. Text effects = drop shadow.
And there you go:

The one with 'pin light' duplicate layer:

Hope this was useful. =)
