The first section begins at the front entrance of the Orto Botanico, follows the perimeter of the Palazzo Corsini exterior gates, and then extends in a western direction toward the Janiculum Hill. This relatively flat area contains thematic gardens, several 18th and 19th century greenhouse buildings, and the mid eighteenth century Fontana dei Tritoni.

From the entrance gate, a large gravel and travertine path leads visitors to the main axis of the garden. The Succulent Garden is located east of the north-south pathway and runs alongside the gates of the Palazzo Corsini. It is roughly arranged in a semi-circular design and contains a pebbled path. The surrounding area of this Succulent Garden is almost entirely covered by grass. Several antique sculptural remnants, including bust and column fragments, are scattered alongside the north-south path.

A Palm Promenade runs along the main axis of the Orto Botanico in an east-west direction . Although the Scala d'Acqua is not clearly visible on the horizon, it is positioned on the same primary axis.

Heading west, three paths perpendicularly bisect the primary corridor. Four circular tufo basins mark the first path and contain stagnant water and aquatic vegetation. The second bisecting path creates a major cross-axis between the Monumental Greenhouse to the north and the Aromatic Garden to the south. Adjacent to the structure is a small garden that consists of vegetation characteristic to the Mediterranean region.

To the south, raised planting beds made of brick and tufo geometrically shape the Aromatic Garden. Adjacent to the Aromatic Garden is a telephone, public toilet, and service shed. The cross-axis path comes to an end at an automobile parking lot that bounds the southern perimeter of the Orto Botanico.

The Fontana dei Tritoni marks both the termination of the principal east-west corridor and the intersection of the third perpendicular path. This is a large, sun-exposed area where the primary landscaping consists of palm trees planted in rows. Travertine benches are placed alongside the gravel pathway that surrounds the fountain. The bisecting trail leads north to the Arancera, which is covered by climbing plants and presently functions as a lecture hall and classroom.

Continuing north, the path leads to the Small Pond area which is filled with water lilies and other aquatic plant species and then on to a small educational building and the Exhibition Greenhouse. A small path branches east from this greenhouse to the Garden of Simple Plants, which consists of a variety of medicinal herbs. Adjoining the Garden of Simple Plants is an open space created by brick pavement. Additional garden beds and greenhouses are laid out in a squared geometric pattern to the east.