Thiess Pty Ltd is a mining company based in South Bank, Queensland, Australia. Established in 1933, it is the world's largest contract miner. It is a subsidiary of CIMIC Group. Thiess was founded as Horn & Thiess by Henry Horn and Leslie Thiess with headquarters in Toowoomba.

Initially the business focused on road-building and earth moving but subsequently expanded into dam construction, open cut mining and other forms of civil engineering.

Thiess delivers under all market conditions with a portfolio that spans leading greenfield mine operations, and optimisation and turnaround contracts at brownfield sites.

With the strongest global track record in diverse mine environments, we leverage rich data, innovations and learnings to solve problems, harness opportunities and deliver best-for-mine solutions. 

According to thiess.com