How were overcrowded cities solved in the 19th century?

For the first half of the 19th century the rural and urban poor had much in common: unsanitary and overcrowded housing, low wages, poor diet, insecure employment and the dreaded effects of sickness and old age

Explanation:

the geography of greece

led to limited interactions with other cultures in the mediterranean

was rich in natural resources and led to repeated invasions from the macedonians

encouraged greater contact with peoples on the southern and eastern mediterranean coasts

caused the greeks to eventually relocate eastward under alexander the great