"... At Night" Or "... By Night"?

I would say 'at' like you've done here: Equestrian Statue Of August The Strong Dresden At Night - Reiter, but I'm no expert.

I think it's a matter of preference - both are correct.

some grammatical forms have always been difficult for me such as the use of gone and went.

On the use of 'at' I found this http://grammar.yourdictionary.com/grammar-rules-and-tips/correct-grammar-usage-of-at.html

Thanks for your answers! Although we say "... bei Nacht" in German (almost similar to "... by night"), "... at night" sounds more harmonious to me. So, if nothing speaks against it, IŽll stay with "at".

"By night" sounds more elegant to me.

Either. But I would use 'By Night' if it was mine.

By night" sounds to my like either it was done by someone named Night or that was your light source. "At" places you in time so that would be my preference.