Answer: The SECOND Continental Congress.
The First Continental Congress had met in Philadelphia in September/October, 1774, in regard to what the colonies saw as "Intolerable Acts" passed by British Parliament after the Boston Tea Party. That meeting had called for a second congress to meet if the British did not respond satisfactorily to the colonists' concerns.
So, when Britain did not yield, the American colonies convened the Second Continental Congress in Philadelphia, beginning in May, 1775. The Philadelphia sessions of the Second Continental Congress lasted till December, 1776. There followed further sessions of the Second Continental Congress that continued through 1781, not only in Philadelphia, but also in Baltimore, Maryland, Lancaster, Pennsylvania, and York, Pennsylvania.