Final answer:
The Stock Exchange building in New York in the 1900s was designed by George B. Post, an American architect known for his many contributions to the city's architectural landscape.
Step-by-step explanation:
The Stock Exchange building in New York in the 1900s was designed by George B. Post. He was an American architect known for his many contributions to the city's architectural landscape. Post's notable works include the New York Stock Exchange building on Wall Street and the Wisconsin State Capitol building in Madison.