Newspaper cartoonists such as Thomas Nast (a talented bigot) were critical of Tweed. Much of what they caricatured was true: the Tammany Ring was rotten. The problem was that the nativist forces they represented were racist and vehemently anti-Irish. So the immigrants saw an attack on Tweed as an attack on themselves and, to a certain extent, they were exactly right, as time would prove.

Each succeeding level surrounding the rotunda is lower in height than the one beneath it. The effect is to give the appearance of being in a much larger and grander building than this actually is.

The decoration was extravagant. Thick plaster reliefs give the building the air of stability and grandeur. No expense was spared. There would have been statues in the niches around the rotunda. The building cost four times as much as the English houses of Parliament and twice the price of Alaska. It was estimated to cost $1 million, and ended up costing $12 million.

Nast was taught by the German-born history painter Theodore Kaufmann. In 1855, he began to work for Leslie's Illustrated Weekly Magazine and studied at the School of Design in the evenings. He published his political cartoons with Leslie until 1858.

In 1860 Nast reported the Heenan–Sayers prizefight in England for the New York Illustrated News, and spent four months covering Garibaldi's campaign in Sicily and southern Italy for the News and the Illustrated London News. In 1862, he joined the staff of Harper's Weekly, where he worked until 1886. During the Civil War, his trenchant anti-South cartoons were widely popular. Lincoln called him 'the Union's best recruiting sergeant.'

It was as a political caricaturist that he excelled, and when the Tweed Ring began to run riot, Nast cut loose. The Ring tried to buy him off, but failed. He made the dollar mark on Tweed's face famous. He invented the symbol of a blazing diamond ring to represent vulgar and showy wealth. Nast created the elephant as a symbol for the Republican Party. The Tweed ring, which was estimated to have stolen $200 million, was broken largely because of him. Nast was also virulently anti-Catholic, anti-pope and he lampooned the Irish as beasts. During Reconstruction, he ridiculed Andrew Johnson. His work became quite bitter in tone.

Nast was a member of the 'silk stocking' Seventh Regiment in New York. President Theodore Roosevelt appointed him consul general at Guayaquil, Ecuador, where Nast died of yellow fever.