The Philadelphia Convention was a meeting of representatives in Philadelphia to fix the Articles of Confederation; however, they ended up writing the new Constitution of the United States that is still in use today.
The Articles needed to be revised because they were weak. They gave Congress very little power, but that was on purpose to stop a big, tyrannical government. However, since they clearly didn't work, the members of the Philadelphia Convention decided to make a new constitution.
The Philadelphia Convention took place from 1787-1789 in the Pennsylvania State House (now called Independence Hall) in Philadelphia.
In all, seventy delegates were invited to the Philadelphia Convention, however some of these could not attend. In all, 55 delegates were present at the Philadelphia Convention, out of which 39 signed the new constitution. These were members from every state except Rhode Island. Some of the most important members of the Philadelphia Convention were:
Benjamin Franklin, who at 81 years old had to be carried around in a chair, James Madison, who wrote most of the Constitution and would later become the fourth President, and Alexander Hamilton, who helped write the Constitution and would later become the first Treasurer of the US.