Travertine is a common dimension and ornamental stone in Budapest, Hungary. It has been exploited from the Roman period and was most intensively used in the last 150 years. To evaluate the durability of travertine; 19th century walls of public buildings were studied by using in situ tests (Schmidt hammer, Duroscope rebound values). These values were compared to laboratory tests of quarry stones. Textural analyses have shown that at least five different types of travertine exist, but two lithologies, the massive travertine and laminated travertine are found in most monuments. Travertine ashlars display various forms of surface alteration and deposition. Black crusts are the most frequent forms of soiling; with framboidal and laminar morphology. Gypsum and calcite are the primary minerals of the weathering crusts. The crust surface is characterised by idiomorphic rosette-like gypsum crystals. On rain washed areas discolouration by leaching, surface dissolution pitting and flaking are also observed. Weathering is also marked by Schmidt hammer rebound values. The average rebound value of 46 of the quarry stone decreases to 30 when laminar black crust and to 28 when dissolved travertine surface is measured.