Why does cat wee smell so bad?

[Zip]

It has to be one of the worst most strongest smelling of all wees.
I woke up today and came out into the dinning room and there was and still is a strong smell of cat wee. Its terrible. One of the cats must have decided to wee on something out here during the night and i dont know where
Why is it so strong and so bad?

 

[Zip]

It's for marking territory .

Evolution!

Its done a damm good job of it too, i can hardly sit out in the room
I thought it was only male cats that mark there territory
We only have girls

 

[Zip]

I think i just steped in it
I walked over a mat and it felt really sticky.
Only time will tell i supose. Mums searching for it now