The British rock band The Who performs Friday in the arena at Boardwalk Hall in Atlantic City on its 50th anniversary tour.

Singer Roger Daltrey and guitarist Pete Townshend will spend the bulk of their golden anniversary year on the road, with an extensive tour. But the pair don’t seem to be on the same page concerning what may happen after this tour ends.

“This time it really is our last,” Daltrey recently told The Daily Express in England. “We’re 70 years old. … I’ve got to the point where I’m having physical problems with my body now, joints going and all that.”

Townshend isn’t sure that the band is ready to stop just yet. The Who recently signed on to headline the final night of the Glastonbury Festival in June.

“We’ve been in this place before,” he recently told Rolling Stone, noting that the band has already played three “farewell” tours. “I don’t know what’s going to happen next.”

Besides featuring one of rock’s greatest singers in Daltrey and one of its most intellectual songwriters in Townshend, the Who’s reputation was cemented by its popular concept albums.

Concept albums carry a single theme throughout.

“The success of the concept album is its ability to cross generations and remain timeless,” said Steve Raymond, music and program director and the midday DJ at classic rock radio station WZXL-FM 100.7.

Below you’ll find a look at some of rock’s most influential concept albums.

Contact: 609-272-7202, Vjackson@pressofac.com Newsday contributed to this report.

ONLINE: To see videos of The Who, David Bowie, Rush, Pink Floyd and other high-concept artists, go to this story at PressofAC.com.