The capital of French Guiana is Cayenne, which was founded 1643. Cayenne has been the capital since 1981.
Cayenne is the largest city in French Guiana and functions as: Houses important commercial buildings.
Cayenne is located at 4.9224° N, 52.3135° W, at an elevation of 33' ft.
Source: https://flic.kr/p/qB3gt2