How to turn white (not blue) skies into black in Lightroom

[batmura]

Hello, everyone. I've recently taken a bunch of photos with the intention of converting them into B&W. As I was shooting during midday on cloudless day, my initial aim was to use a polarizer to darken the blue skies in hopes of turning them into black in post processing but the it was so sunny that the skies all turned out pure white. There are also no clouds, so I was wondering if there's any way to turn them into black so as to highlight the main subject (a skyscraper in this case) better.

I do not have Photoshop, so any help within Lİghtroom and Silver Efex Pro 2 would be appreciated.

Cheers!

 

[snowbear]

A red filter (before B&W conversion) should darken them a bit but I wouldn't expect black. I don't think it's in LR, but there's one in PS, or just get a real red filter and put it on the lens.

 

[smoke665]

Without seeing the image, not sure that this will work but it's a start. In LR use the graduated filter tool. Improve Your Images with the Lightroom Graduated Filter Tool