Proline Decorative Concrete Systems 2TRC 20" x 20" Seamless Travertine Course Concrete Stamp without Handles Concrete Stamp. Travertine is a sedimentary rock. Extensive deposits are found in Tivoli, Italy. Travertine is a porous finish with numerous cavities. Proline can give you the look of this beautiful natural resource in a fraction of the cost. The Italians say "Il tempo e denoro" or "time is money". Why pay a high cost for imported stone, when Proline has replicated the same look with an easy to install application.