Ancient BeginningsThe Macellum Magnum was a large, two-story indoor food market constructed by Emperor Nero in 59 CE on Rome's Caelian Hill, primarily for selling meat and fish. It was considered one of such an important structure It was even found on Roman coins from that time period. Much of its architecture is known from coins of the time. It likely had a domed, circular section surrounded by a large square area with a two-story portico supported by 22 inner columns and 36 outer columns.