What is the opposite for "light up"?

[Snappy]

What is the opposite for "light up"?
I think I can say, "Let's light up the building."
Do you ever say, "Let's light down the building"?

[PROESL]

What is the opposite for "light up"?
I think I can say, "Let's light up the building."
Do you ever say, "Let's light down the building"?

We would just say "turn off the lights".

[susiedqq]

or -

darken the building

put out the lights