Caligae

Caligae (Latin; singular caliga) are heavy-soled hob-nailed military boots known for being issued to Roman legionary soldiers and auxiliaries throughout the Roman Republic and Empire. Worn by all ranks up to and including centurions, no other shoes in history are as symbolic of the expansion of an empire as the famed caligae.

The caligae can resemble modern sandals but were actually marching boots. Sandals proper were not worn outside by the Romans, rather they were regarded as indoor footwear, sometimes even carried by slaves to be changed into for such things as banquets.

Design
The open design of caligae allowed for the free passage of air to the feet and, unlike modern military boots, was specifically designed so as to reduce the likelihood of blisters forming during forced marches, as well as other disabling foot conditions like tinea or trench foot. Socks were not normally worn with caligae, although in colder climates such as Britain, woolen socks were used.

Caligae were constructed from three leather layers of which the top formed the outer shell. They were laced up the center of the foot and onto the top of the ankle. Additionally, iron hobnails were hammered into the soles, to provide the caligae with reinforcement and traction.

Shoes outside the military
Various other types of leather footwear were worn within the Roman empire. The carbatina was a sandal made from one piece of leather with a soft sole and openwork upper fastened by a lace. A soccus was a sole without hobnails and a separate leather upper. A calceus was a hobnailed footwear secured by laces. A solea was a simple sandal with a thong between the toes and a hobnailed sole. Women wore sandals similar to those of men, but they were of softer, finer leather. Winter shoes were usually cork-soled. Sometimes the soles were thickened to provide the imitation of height.