Saint-Denis-lès-Martel (French pronunciation: [sɛ̃ dəni lɛ maʁtɛl], literally Saint-Denis near Martel; Languedocien: Sent Daunís de Martèl) is a commune in the Lot department in south-western France.

It is watered by two tributaries of the Dordogne, the Sourdoire which borders the communal territory to the southeast, and the Tourmente.

It is in the present territory of Saint-Denis-lès-Martel, on the slopes of the Puy d'Issolud, formerly Uxellodunum, the last battle for the conquest of Gaul by Julius Caesar occurred during the summer of 51 B.C.

This ultimate victory in the land of the Cadurques, that marked the beginning of the Roman occupation of all Gaul, was acquired by a ruse of Caesar who besieged the Gauls of the Uxellodunum oppidum with his legionaries and dug underground galleries that deprived the occupants of their main water supply (the current fountain of Loulié).

On April 26, 2001, the work of the team of the archaeologist J.P. Girault was officially recognised by the Ministry of Culture in Toulouse, identifying Uxellodunum with the puy d'Issolud located in the Lot on the right bank of the Dordogne river in the commune of Vayrac and partly in that of Saint-Denis-lès-Martel, source of the Fountain of Loulié, place of the siege and the capture of the source by the Romans.