Doesn't it remind you of an iceberg or maybe an icicle, or a crystal?
I started off with a coat of GOSH Holographic Hero (an awesome polish! sent to me in a swap by @gracilee on Instagram); then I sectioned off the outline of the building using striping tape. Next step colour in the building and the sky parts (using a basic white and blue by Jezy - a cheapie brand with a great range). To finish the look I used a sliver striper to go over the outline again and make it "pop", then topped the whole design with a bit of Essie Perlification, and of course Seche Vite!