WHERE: Trans Alaska Pipe-line, Fairbanks, Alaska.

WHAT: The 800-mile-long Trans Alaska Pipeline System is one of the largest pipeline systems in the world.

Starting in Prudhoe Bay on Alaska's North Slope, the pipeline stretches through frozen tundra, boreal forest, rivers and mountains to Valdez, the northernmost ice-free port in North America.

In Valdez, the petroleum is loaded aboard tankers for the journey to U.S refineries.

The 48-inch diameter pipeline attracts visitors from around the world with portions visible along the 368-mile Richardson Highway between Fairbanks and Valdez. The pipeline crosses three mountain ranges and over 800 rivers and streams. When it was built in 1977, the pipeline cost $8 billion, the largest privately funded construction project of its time.

On their late summer cruise through Alaska's Inside Passage, Patricia and Eugene Kang of Kane'ohe visited the pipeline in Fairbanks, where the Alyeska Pipeline Service Co. that built and operates the system has a visitor center. More than 90,000 people visit the center each year to learn about the workings of the pipeline, how it was built and how it is maintained.

Seeing the pipeline was one of the highlights of the Kangs' great Alaska adventure along with the country's wildlife. "Alaska is awesome," said Patricia Kang. "We've been there three times with our friends and can't stop talking about our experiences, they've been endlessly good."

If you go: A viewpoint for the Trans Alaska Pipeline is about 10 miles north of Fairbanks at the Alyeska Pipeline Service Co. Visitors Center. The center is staffed 8 a.m. to 5 p.m. Memorial Day through Labor Day. 907-450-5873. www.alyeska-pipe.com.

(In Valdez, bus tours of the marine terminal of the pipeline are daily from April to October. Call the Valdez Convention & Visitors Bureau at 907-835-2984.)