It's been 50 years since we learned to love "Elsa"...

The story of "Born Free" -- a book and film that forever changed the way we think about wildlife. What has happened to lions since this story? And what has happened to the people featured in the film? NATURE...7pm

In the next episode of Wagner's Ring Cycle - Das Rheingold, the mysterious hero Siegmund finds shelter in the familiar arms of a lonely woman named Sieglinde...GREAT PERFORMANCES AT THE MET...8pm

Where do you start to rebuild Ground Zero?

NOVA captures the behind-the-scenes struggle of architects and engineers in an epic story of  innovation, engineering and the perseverance of the human spirit. With extraordinary access granted by The Port Authority of New York and New Jersey, "Rebuilding Ground Zero" follows the five-year construction of the Freedom Tower and the World Trade Center Memorial...culminating with the topping off ceremony at the hallowed site. NOVA: REBUILDING GROUND ZERO...7pm

In a historic first for any major performing arts institution in this country or abroad, the Metropolitan Opera this season presents Wagner's THE RING CYCLE...beginning tonight at 8pm

Let the Ring Cycle begin...

A documentary by Susan Froemke, shot over five years, captures the unprecedented challenges of bringing Director Robert Lepage's electrifying production to life. The stakes could not be higher as the Metropolitan Opera tackle Wagner's Ring Cycle. An intimate look at the near impossible theatrical and musical task of staging opera's most monumental work, WAGNER'S DREAM chronicles the quest to fulfill Wagner's dream of the perfect Ring...8-pm 

Alas, McCartney joins the "standards" crowd...

GREAT PERFORMANCES joins Sir Paul for an intimate concert recorded at the historic Capitol Studios in Los Angeles, featuring performances of such standards as "I'm Gonna Sit Right Down and Write Myself a Letter,"...really...Friday at 8pm

Meanwhile, Pearl Jam rocks it out on Austin City Limits, Saturday at 10pm                                                                       

POV follows the four-year journey of childhood friends who join the National Guard after graduating from high school. As it chronicles the young men's transformation from restless teenagers to soldiers looking for roadside bombs in Afghanistan, to 23-year-old combat veterans trying to start their lives again, the film offers an intimate look at the young Americans who fight our wars, the families and towns they come from -- WHERE SOLDIERS COME FROM, Saturday at 11pm 

This weeks ON STORY features the creators behind the explosions of CON AIR, GONE IN SIXTY SECONDS, HULK, ZOMBIELAND and MACHETE...and debate what makes a great action movie. Sunday at 5:30

The REALLY BIG NEWS this weekend is BROADWAY OR BUST...cameras follow talented high school performers, the best in the country, to New York, where they meet their colleagues face-to-face and begin competition for a Broadway break. As day one unfolds, they learn a new opening number from director Van Kaplan and choreographer Kiesha Lalama, get one-on-one coaching in music, theater, dancing and acting from some of Broadway's top talent - including Leslie Odom, Jr. ("Smash"; Rent); Michael McElroy (Tony and Drama Desk Award nominations for Big River; Rent, Miss Saigon); Liz Callaway (Tony Award nomination for Baby; Cats, Miss Saigon) - and prepare for their solos in front of an influential group of judges. The episode ends with students wondering, "Do I have what it takes to make it on Broadway?" Sunday night at 7pm 

there will be no balloon drop following his speech...

John Kerry, Joe Biden, Natalie Portman and Scarlett Johansson round out the names of speakers who will appear...culminating with President Barak Obama's acceptance of the nomination...and PBS has the whole thing - gavel to gavel. Tonight starting at 6pm

Back in the fold, Mr. Clinton's at center stage...

It's Day 2 of the Democrat National Convention, covered gavel-to-gavel on PBS...
tonight featuring sexual-health activist Sandra Fluke, Minority Leader Nancy Pelosi,
and the Democratic candidate battling Scott Brown for a Massachusetts Senate seat Elizabeth Warren...all leading up to Bill Clinton. Coverage begins during PBS Newshour at 6pm

Power Politics...Part Deux...

Tonight's Democrat National Convention, covered gavel-to-gavel on PBS, features San Antonio Mayor Julian Castro with the keynote, and First Lady Michelle Obama stepping us as a "character witness" for her husband, the president. Coverage begins during PBS Newshour at 6pm