There's a picture of the replica "pier" on This Site It's the fifth picture down the page.
I think it was George Formby's father who coined the phrase "Wigan Pier" in his music hall act and the rest - as they say - is history - the phrase stuck and Wigan became the butt of many a music hall joke. It's actually well worth going round the exhibition at what is now a tourist trap!
George Formby sang a few songs about Wigan - probably the most famous one was "In a little Wigan garden" which he sang in "No Limit!" - the one about the TT races in th' eyeler man (as we say round our way). Another one was "On the Wigan boat express"