Hi stamphop,
I found your Colombia stamp in StampWorld:

Colombia #760, 1956, Brown/blue, PERF 13. Printed in Colombia.
In Mint it is valued at $0.33.
Here is a bit of history about the Department of Choco, the area
depicted on the map:
The
Chocó Department is divided into 30 municipalities , 147 districts , 135 police posts and numerous villages and populated places . The municipalities are grouped into 16 notary areas, with an additional major notary based in Registry Quibdo and 3 sectional registry offices located in the municipalities of
Quibdo ,
Istmina and
Nuquí ; a judicial district , Quibdo , with 2 headers Judicial Circuit in Istmina & Quibdo . The department forms the constituency of Choco, which is known for producing platinum.
This picture is in Quibdó. I only added it because I can't figure out how that building is still standing! LOL

Quibdó is the capital city of Chocó in the western part of Colombia, on the River Atrato . Quibdó has an area of 3,337.5 square kilometers with a population of 100,000 consisting mainly of Afro Colombians and Zambo Colombians. Wikipedia
A bit of architecture in Quibdó

Afro Colombians in Quibdó
Hotel Los Balcones in Istmina. 
Istmina, Colombia is a municipality located in the department of Chocó ,founded in 1834 by Juan Nepomuceno Mosquera, First named San Pablo. In 1903 the name was changed to Istmina. It has an area is 2480 square kilometers and has an average temperature of 25.9 ° C. It is located 75 kilometers from the provincial capital Quibdó and 79 meters above the sea. Istmina is located mostly on the middle reaches of the San Juan River, and some on the the basin of the River Atrato.
Nuqui Choco from the air.

Nuquí is a Colombian municipality located in the department of Chocó, founded in 1917 by Johnny Castro and has been a Municipality since 1919. Nuqui is visited by domestic and foreign due to its natural beauty, local culture and cuisine. Wikipedia

Google:
nuquí chocó colombia, 0n the
Image tab, you will be glad you did. Plum beautiful!