Y these buildings in the landscape pix looks flat??

[Kit]

I think people before me had covered most of the critical points for you to improve your shots in future. You just don't have good ambient lighting falling on the building. Besides, the building is back lit, sun is shining from the back. In essence, your building is in shadow so for your camera to expose the facade correctly, the sky gets clipped badly.

I'd rather not having you to believe that post processing can save these photos. Knowing your light is way more important than trying to save something fundamentally flawed and yes, these photos have other issues (mainly composition) other than the poor lighting.

 

[Kit]

BTW, its not entirely true that midday timing should be avoided. In some instances, strong sunlight actually work nicely with some buildings if you know how to expose it to your advantage. Again, get to know your light and familiarise yourself with various conditions.

This was taken close to noon time, with the building facing the sun directly. I did had a blue sky and the tones were further deepened with a 2 stops under exposure. That would also prevent the brighter part of the building from being overexposed.

 

[hisoman]

Try to shoot in the morning. You will get better light for arhcitecture photography.