HO scale is the most popular size of what?

More Questions:

What Philadelphia building appears on the back of the US $100 bill?

What 1990's fad involved something known as a slammer?

What kind of sporting event is divided into chukkas?

What breed of dog is Snoopy?

In Shakespeare's "The Taming of the Shrew', what is the name of the shrew?

Which continental South American country borders Panama?

Thursday Island is located in the Torres Strait off the coast of what country?

What is the common word for a weight suspended from a pivot that can move freely?

Mt. Rainier is one of sixteen volcanoes in the world that is classified as what?

Which of David Bowie's eyes has a permanently dilated pupil?

To what tribe did Chief Tecumseh belong?

What firm made the B25 Micro Computer?

What color is human blood that isn't oxygenated?

Which of Shakespeare's plays involves a pound of flesh?

Bangui is the capital of which land-locked African country?