The house at 1340 Pennsylvania Street was built in 1889 for Isaac and Mary Large, during Denver's rapid growth after the Colorado mining booms. Architect William Lang combined elements of Queen Anne and Richardsonian Romanesque design, using rough stone, ornamental woodwork, stained glass, and an asymmetrical plan. The financial crisis that followed repeal of the Sherman Silver Purchase Act damaged the Larges' fortunes. James Joseph Brown purchased the house in 1894 after mining success in Leadville brought his family substantial wealth.

J.J. Brown's engineering and management work was connected to the Little Jonny mine of the Ibex company, whose gold production transformed the family's circumstances. The title to the Denver house was later placed in Margaret Brown's name. Margaret used wealth and social connections to support education, labor relief, juvenile justice, women's suffrage, and charitable causes. The family traveled frequently and sometimes rented the residence, so it was both a private home and a flexible asset rather than a static stage for a single idealized domestic life.

Margaret became internationally known after surviving the sinking of RMS Titanic in 1912. She escaped in Lifeboat 6, advocated for survivors, helped organize relief aboard the rescue ship Carpathia, and later supported recognition of the crew. Newspapers amplified her actions, while the nickname “the Unsinkable Molly Brown” became popular only after her lifetime through books, theater, and film. The familiar legend captures her energy but can obscure a longer record of activism, multilingual travel, wartime relief, political ambition, and engagement with reform movements.

Margaret and J.J. lived increasingly separate lives, and the house served various occupants. Margaret died in 1932, and the property was sold soon afterward. It became a rooming house and was adapted for other institutional and residential uses. Subdivision, hard use, and changing neighborhood economics placed the building at risk. By 1970 demolition appeared possible, reflecting a period when many Victorian houses in central Denver were lost to redevelopment and historic preservation had limited formal power.

Concerned residents organized Historic Denver in 1970, acquired the property, and led a research-based restoration using photographs, physical evidence, and surviving materials. The Molly Brown House Museum opened in 1971 and became an early catalyst for preservation in the city. Later work has refined the interiors and expanded interpretation beyond the Titanic story to address mining wealth, domestic labor, reform, family life, and mythmaking. The house is significant both as Margaret Brown's home and as a monument to the preservation movement that saved it, demonstrating how public memory is constructed, challenged, and renewed.