Pericles had built the Long Walls. These were two parallel fortified walls with tile roofs. The Long Walls connected Athens with its seaport of Piraeus some five miles, or eight kilometer, away. Having the long walls meant Athens could get supplies even in times of war. This is a primary example of Delian League money being spent on the city.
Pericles plan- Crowd EVERYONE into Athens behind the walls of the city. The navy and Long Walls allow food into Athens
Why did it fail?
A PLAGUE broke out – killing 1/3 of the population including Pericles. Much of the land was ruined.