Bastion (noun)

1. A projecting part of a fortification, built at an angle to the line of a wall.
2. A fortified area or position.
3. A person or group that strongly defends a particular belief or principle.

Origin:

From the french word "bastion" meaning "stronghold".

Examples:

1. The castle had several bastions for archers to shoot from.
2. The city wall had a bastion at each corner.
3. The city was surrounded by a bastion of mountains.
4. The company's CEO has become a bastion of free-market economics.
5. He was a bastion of traditional values.