It is hand drawn on black cardboard.
Leno Battista Alberti delineated the city of Rome used the instrument made by his own based on the principle of perspective and mathematics. He recorded the lineation of the walls, the river , the streets, the temples the outlines of the hills of the city Rome. His mathematical way of delineating is functional without measuring the actual distance, and his map is remarkable precise compared to the easiness of the way of measuring.
The instrument had two parts, a circle that acting as horizon, which indicates the size of the map, and a rod “spoke”. Each of them was divided to certain subdivisions, which in his description he divided them into 50 degrees and 4 minutes for one degree each to make it precise. The horizon was marked the four directions, the east, the west, the south and the north.
Then he set several points on the city walls and rivers based on their corners and the point that their curvature reached the highest. He also marked several important location in the city such as the Portas. He chose the capito as his measuring point because it is the tallest building in Rome and he could oversee all the locations from there. By using the rule of perspective he measured the relatively distance and angle of those locations from his standing point on his instrument, and filled in the table with the measurements. After that, he used those measurements to mark those points on his map of Rome and connects them based on the corners and curvatures. In this way he made his delineation of the city Rome.