Is there any steam locomotive longer than the Union Pacific 4-8-8-4 Big Boy?

My friend had informed me that there was a steam locomotive that was longer than the Big Boy but he didn't give me an accurate name, year, company, or wheel configuration. I have surfed the internet but not very well as I couldn't find any names. It doesn't have to be operational either, I just want to know if they designed anything larger and where can I find an image.