Denmark has continuously used the same flag - the Dannebrog - for 800 years since the Medieval European era.
The Danish flag's red background represents courage, while the white of the cross stands for peace. The cross was a common symbol on European flags when Christianity spread through the continent.
The flag was honoured at a ceremony in Vordingborg and was attended by the country's royal family.
South Africa, on the other hand, has the 26th youngest country flag in the world - our rainbow flag was created as we said goodbye to Apartheid in 1994.
See below for more of the world's oldest country flags according to this Wikipedia list (dates according to when the current flag was officially used):
QUICK GUIDE TO NETHERLANDS: Going Dutch for your next Euro trip
4. United Kingdom
QUICK GUIDE TO ARGENTINA: Visa-free travel for South Africans
10. Belgium and Tunisia (Tied)