The Irish immigration back then was mainly because of the potato famine issue.
Answer:
Romans preferred a much more regular, rational layout and plan. They inherited the Greek tradition of city planning on rectangular grids but they refined it to include more open space and central public focus: the forum, a kind of city center where the most important civic buildings, temples and monuments would be located.
Http://www.racismreview.com/blog/2011/04/01/african-americans%E2%80%99-social-racial-identity-under-...
