This week on WGCU TV

. Great Performances: "King Lear" - Wednesday, March 25, 8 p.m.

William Shakespeare's unrelenting tragedy is widely considered one of the playwright's most enduring and haunting works. Ian McKellen is Shakespeare's tragic titular monarch in this special television adaptation of the Royal Shakespeare Company production.

. Great Performances: Eric Clapton Crossroads Guitar Festival Chicago - Thursday, March 26, 8 p.m.

Clapton and the world's leading guitar gurus return to the stage for a new gathering in Chicago.

. Untold Stories: "Sanctuary Islands: The Sanibel Legacy" - Friday, March 27, 8:30 p.m.

With more than 60 percent of the island designated as forever wild, Sanibel Island boasts an incredible history of conservation. From its national wildlife refuge and aggressive land acquisition programs to its acclaimed wildlife clinic and 35 years of home rule, Sanibel reflects nearly a century of efforts to preserve its natural wonders. Grass-roots determination and diligent environmental awareness created an island sanctuary in spite of plans to the contrary.

. Glen Campbell in Concert - Saturday, March 28, 11 p.m.

The superstar performs "Rhinestone Cowboy" and other hits with the South Dakota Symphony Orchestra.

. Masterpiece Classic: "Little Dorrit (Part 1)" - Monday, March 23, at 8 p.m.

Charles Dickens' most moving love story — with its timely theme of chronic debt and financial collapse — comes to life in this new, five-part miniseries starring Matthew Macfadyen, newcomer Claire Foy and Tom Courtenay.

. Antiques Roadshow: "Chattanooga (Part 1)" - Monday, March 30, 8 p.m.

An 1826 Tennessee hunting horn; a

Regency cellarette once owned by poet Lord Byron; and an heirloom necklace adorned with a five-carat diamond. Reenactors fire a mid-19thcentury cannon.

. NOVA: The Last Extinction - Tuesday, March 31, 8 p.m.

Scientists now believe that the extinction of more than 34 types of large prehistoric animals in North America wasn't caused by climate change or human hunters, but

by the breakup of a massive

comet over the Great Lakes region at the end of the last Ice Age. NOVA explores this provocative new theory.