Why did Daniel Burnham recommend preserving Manila’s old Spanish walled city?

When the United States government asked Daniel Burnham to create a "Beautification Plan" for Manila following the Spanish-American War, he recommended the preservation of the city's old Spanish walled city, Intramuros.

Burnham’s recommendation was rooted in his approach to urban planning, which emphasized the creation of a beautiful, efficient, and orderly environment. By preserving the historic walled district, he sought to integrate its unique character into a broader, comprehensive plan that utilized familiar City Beautiful movement components. These included a system of parks, a network of diagonal roadways designed for traffic efficiency, and a formally arranged civic center complex to serve as the heart of the community.1