HE was the poet laureate of the Rocky Mountains: Albert Bierstadt, who immortalized the American West on canvas.Born in Germany, the son of a German barrel maker who came to New Bedford, Mass., with his family, Bierstadt taught himself to draw. He gave lessons, mastered painting well enough to earn the money for passage back to Germany to study in the art mecca of Dusseldorf. By the time he reached Lake Lucerne and painted its Alps-shadowed splendors, he was ready to take on America's soaring mountains. As you stroll through the National Gallery's exhibition "Albert Bierstadt: Art & Enterprise" there is one room especially that will stop you in your tracks. It is a room vast enough to hang several of Bierstadt's more stupendous paintings. But the one that halts you like a lion's roar is "Storm in the Rocky Mountains, Mount Rosalie," done in 1866. It looms over the room, a painting so dramatic and compelling that you want to walk right into it, past the native Americans on horseback who look so tiny in the green foreground of the mountains, up past the pines and rocks, to the very edge of the lake on which light floats. Gold sunlight pours down Mount Rosalie's rocks and gorges at the right and gilds its peaks at the left. It is the brooding blue storm that fills the upper part of the painting with ominous navy and purple clouds that awe the viewer . It is difficult to look away from this breathtaking painting. The Bierstadt exhibition, which contains over 70 of the artist's celebrated works, is the most extensive show ever done on the painter who scaled the heights of fame but then fell out of style. It includes his important early painting, "Lake Lucerne," that led to his Western works. That painting, lost for over 100 years, was rediscovered and donated this year by Richard M. Scaife and Margaret Battle as a 50th-anniversary gift to the gallery. "This gallery existed for 50 years without a Bierstadt," sighs its director J. Carter Brown, "and that was of course a thorn in the flesh." The gift "added to the show the missing lynchpin between Bierstadt's European skill and the sense of grandeur he was soon to apply to our own outdoors." Other Bierstadt landmarks in the show are "The Last of the Buffalo,The Domes of the Yosemite" and "The Rocky Mountains, Leander's Peak." The exhibition was organized by the Brooklyn Museum in association with the National Gallery, where it will close on Feb. 17. Bierstadt was aware of the dramatic impact of his paintings. In fact he treated them like enormous theatrical showpieces when he brought them back from the West to New York. Like Frederick Church, who also made his reputation painting vast landscapes of the Americas ("Heart of the Andes"), Bierstadt put his landscapes on display in New York, promoted them, sold tickets, lit them like performances, and charged an admission fee. Linda Ferber, curator of American paintings at the Brooklyn Museum co-curated the show with Nancy Anderson, the gallery's assistant curator of American and British painting. In her catalog essay, Ms. Ferber says that Bierstadt's "Great Pictures" made him rich. As word spread of the Western panoramas done by Bierstadt, one critic noted he had already "copyrighted nearly all of the principal mountains." Soon Bierstadt, whose paintings filled whole walls in millionaire's mansions, had a mansion all his own. He built a great Victorian castle on the Hudson River in Irvington, N. Y., that was so lavish he could live the same lifestyle as his patrons. Supporting it eventually cost him his reputation. He built his mansion at the height of his fame, in 1866, just before his marriage. By the time his river castle burned down in 1882, the demand for his magnificent Western paintings had pretty much gone up in smoke as well. His severest critics had been chipping away at his reputation since the peak of his success and by the mid-1870s, as critic William Howe Downes noted, "the change in taste and fashion ... combined to relegate Bierstadt's name and fame to relative obscurity. Yet his pictures are as good today as they ever were.... In the history of American landscape art, the name of Bierstadt will always be entitled to a position of a certain prominence."