LONDON — Art lovers will soon be able to take a picturesque boat ride on the Thames River between two of the most important museum exhibitions of the year. Tate Britain is celebrating the centenary of Francis Bacon, widely regarded as Britain’s greatest painter, by bringing together 70 works never before shown in one exhibition and representing every period of his life. Later this month, the museum’s provocative young sibling, the Tate Modern, will feature the first major exhibition dedicated to the late works of Mark Rothko (1903-70), the American painter who created a new and impassioned form of abstract painting. The show includes more than 50 paintings and works on paper from between 1958 and 1970. For the first time, 15 of Rothko’s monumental Seagram murals will be shown alongside more than 30 other landmark paintings. Coincidentally, sales of Bacon’s and Rothko’s paintings broke records for sales of postwar art at Sotheby’s last May, a work by Bacon fetching $52.7 million and one by Rothko, $72.8 million.

“What’s particularly interesting about this Bacon show,” a Tate Modern curator, Matthew Gale, said, “is that it looks back on his career in light of new research that emerged with the opening up of his studio and its contents since his death. Altogether new aspects of the man have been revealed that shed enormous light on his visual lexicon.”

Bacon was born in Dublin to English parents. His studio was recently dismantled and then reconstructed within the Dublin City Gallery. As a result, scholars have been able to evaluate more than 7,500 objects related to the artist. These include illustrated publications, photographs, press cuttings, notes, drawings, medical textbooks, books on psychic phenomena, artists’ materials — among them several pairs of corduroy trousers used to apply paint — and slashed canvases. Through them, scholars now better understand Bacon’s working methods and sources of inspiration. Some objects will be exhibited in an archival room adjacent to the paintings’ galleries. Mr. Gale co-curated the exhibition with Chris Stephens, head of displays at Tate Britain.

“We learned that he took far longer to paint his works than he admitted to,” Mr. Gale said. “And that he extensively used photographs and other illustrative material. He drew inspiration from things as disparate as the works of Michelangelo and Eliot’s ‘The Wasteland.’ We now better understand the incredible processing that he went through to make his art.”

To demonstrate the relevance of Bacon’s sources, such as clinical representations of animals and emotional landscapes, these objects will be displayed next to his representations of the body. In “Three Studies for Figures at the Base of Crucifixion” (1945), which features writhing half-human, half-animal forms, he overthrew artistic conventions by using the triptych format of Renaissance altarpieces to show the evils of man, rather than the virtues of Christ. While this work has long been at the Tate, in this exhibition it will be shown for the first time with other related, celebrated paintings and triptychs including “Study after Velazquez’s Portrait of the Pope Innocent X” (1953), “Crucifixion” (1965), and “In Memory of George Dyer” (1971).

“What I find amazing,” Mr. Gale said, “is that even after all the preparation for this exhibition, looking at Bacon’s paintings still makes my spine tingle. I never stop being overwhelmed.”

The curator of Modern and Contemporary art at Tate Modern, Achim Borchardt-Hume, who organized the Rothko exhibition, is equally passionate about his subject. “The key to this period,” he said, “is the 30 monumental Seagram murals that Rothko made between 1958 and 1959 for the Four Seasons Restaurant [within New York’s Seagram building]. He never gave them to the restaurant because he eventually felt they wouldn’t be appropriate there, and toward the end of his life donated nine of them to the Tate because of his love of our Turners.”

Rothko wanted the works to be shown together, and so the museum created the Rothko Room. Other important Rothko murals were borrowed from Japan’s Kawamura Memorial Museum and Washington’s National Gallery for this exhibit. “It is a huge coup for the Tate to have the loan from the Kawamura, which never lent works to an international exhibition before,” Mr. Borchardt-Hume said. Shown with Rothko’s “Black-Form” and “Black on Gray” paintings and his “Brown on Gray” works on paper, the result is a very different impression of the artist.

Maintaining his focus on formal elements, such as color, shape, balance, depth, composition, and scale, Rothko began to darken his palette dramatically during this period, turning from bright, intense colors to deep red, maroon, brown, and black. He also turned from closed forms to open ones that look like a threshold or entrance. “I believe he would have wanted viewers to see these together,” Mr. Borchardt-Hume said. “Like his chapel in Houston, they create a meditative experience. They need time to be appreciated. Only as you look carefully do your eyes begin to adjust. It’s a curious dynamic, almost like listening to music.”

After London, the Bacon exhibition will travel to the Prado Museum in Madrid from February 3 to April 19, and then to the Metropolitan Museum of Art from May 18 to August 16. The Rothko show will travel to the Kawamura Memorial Museum of Art in spring 2009.

Francis Bacon, until January 4 at the Tate Britain, tate.org.uk/britain.

Mark Rothko, September 26 to February 1 at the Tate Modern, tate.org/ukmodern.