Which of these hills was not one of the Seven hills of Rome?

The Pincian Hill is a hill in the northeast quadrant of the historical center of Rome. The hill lies to the north of the Quirinal, overlooking the Campus Martius. It was outside the original boundaries of the ancient city of Rome, and was not one of the Seven hills of Rome, but it lies within the wall built by Roman Emperor Aurelian between 270 and 273.

Several important families in Ancient Rome had villas and gardens (horti) on the south-facing slopes in the late Roman Republic, including the Horti Lucullani (created by Lucullus), the Horti Sallustiani (created by the historian Sallust), the Horti Pompeiani, and the Horti Aciliorum. The hill came to be known in Roman times as Collis Hortorum (the "Hill of Gardens"). Its current name comes from the Pincii, one of the families that occupied it in the 4th century AD.

The seven hills are:

1. Aventine Hill

2. Caelian Hill

3. Capitoline Hill

4. Esquiline Hill

5. Palatine Hill

6. Quirinal Hill

7. Viminal Hill