Near the Exploratorium in San Francisco, California stands a "Roman" ruin. Originally constructed in 1915 for the Panama-Pacific International Exposition held to celebrate the completion of the Panama Canal.
The architect responsible for the structure said that in addition to creating a beautiful focal point for the Exposition, the Palace was created to demonstrate "the mortality of grandeur and the vanity of human wishes." It consisted of an exhibition hall which held the work of many living artists (largely dominated by the Impressionists), a colonnade, and the rotunda. Near the structures a lagoon was created as a reflecting pool to add to the artistic effect of the buildings. It was designed in a loose corinthian style, and like the art it contained, was a free-spirited and romantic interpretation. The rotunda was decorated with paneled reliefs by Bruno L. Zimm, and the colonnade was adorned with weeping figures (thought to symbolize the woe of life without art) created by Ulric Ellerhusen.
The Palace was intended to be a fairly temporary structure. Though it was built on an atypically strong steel structure, the majority of the exterior was created with staff laid on a wooden structure. This created the desired faux-marble appearance, but meant that the palace would not last much longer than the Exposition it was built for.
Almost immediately after the close of the Exposition (December 4, 1915), the Fine Arts League was formed to raise money in order to preserve the Palace. It was used to exhibit art for many years, and the fading murals were replaced during the Great Depression. Unfortunately the League was unable to do any more, and bizarre things like lighted tennis courts started to appear in and around the Palace. Without funding, the palace was reduced to ruin, and was deemed unsafe for public use. It was requisitioned by the Army during World War II for supply storage, and then was used as motorcade parking by the United Nations.
Oddly, a new motion was started in the late 1940's to preserve the Palace in its current ruined state. The original architect did not support the idea, instead wanting the entire structure save the rotunda to be torn down, and redwoods to be planted to enclose the degenerating dome.
Neither of these plans were seen to completion. In 1957 a new plan for full restoration was formed. In 1964 the structure was demolished, and plans for reconstruction started, with projected costs at ten times the original budget used in 1915. The new plan was to use light-weight concrete to recreate the entire structure, sculptures and art included.
In 1966, the new Palace of Fine Arts was completed. Though the colonade and rotunda were reopened with great fanfare, the exhibition hall remained empty for a number of years. In 1968 Frank Oppenheimer came to San Francisco hoping to create a museum of science, and the city's Park and Recreation Commission approved his plan to use the Palace's exhibition hall in August of 1969. In September of the same year, the Exploratorium opened its doors, and since then it has become one of the world's most successful educational science museums, drawing tourists from every corner of the globe. The Palace is now one of San Francisco's most popular tourist attractions, and receives city funding to ensure its preservation.
If you're interested, pictures of the Palace of Fine Arts are available at the first source cited below.