How can I express a thought of a distance between two cities measured as a length of a line segment connecting them on a map, as opposite to distance of the two cities measured as length of a road connecting them?

a) in a straght line

b) as the crow flies

c) length of beeline

context: Distance between Paris and Rome is 1104 km measured in a straight line.

Thank you.

How can I express a thought of a distance between two cities measured as a length of a line segment connecting them on a map, as opposite to distance of the two cities measured as length of a road connecting them?

a) in a straight line

b) as the crow flies

c) length of beeline

context: Distance between Paris and Rome is 1104 km measured in a straight line.