In this study, horasan and lime plasters of Zeyrek Çinili Bath (16th c.) in İstanbul built by Mimar Sinan, considered as the master architect of the Ottoman Empire, were investigated to determine application techniques of plasters, basic physical properties, raw material compositions, microstructural properties and hydraulicity of plasters, mineralogical, chemical compositions of binders, pozzolanic activities of crushed brick aggregates by using standard test methods, binocular microscope, XRD, SEM-EDS and TGA. Multilayered plaster application on the wall surfaces of the inner spaces of the bath was classified as lower level and upper level plasters. The lower level plasters are composed of two horasan plaster layers. The first layer is rough while the second layer is fine. Glazed tiles are adhered on the second layer of the horasan plasters by glazed tile adhesives. Hence, all horasan plasters are original and not repaired. The upper level plasters are composed of a horasan plaster layer with one or two lime plaster layers. The plasters of domes are consisted of a rough horasan plaster layer with one fine lime plaster layer. Horasan plasters used in all spaces of the bath have no significant differences in their physical properties, mineralogical, chemical compositions, microstructural properties, pozzolanicity and hydraulicity. Horasan plasters are high porous and low dense materials. The layers of horasan plasters used in the bath are well adhered to each other. Brick aggregates of horasan plasters have good puzzolanic properties. Hence, most of the horasan plasters are hydraulic.