article_snippet: The Pantheon, Trajan's Market and the Colosseum have remained standing for nearly 2,000 years.
article_snippet: In the concrete walls of Trajan's Markets, constructed around 110 CE, this mortar binds cobble-sized fragments of tuff and brick.
article_snippet: Those under construction were yellow.
article_snippet: As a result, massive marble blocks were constantly being moved through the city, causing congestion in the streets.