We model the subsurface thermal field of the Apollo 17 landing site in the Taurus-Littrow valley focusing on local topographic effects and refraction of heat. Topographic effects have been accounted for in original reports, but the refraction of heat due to local thermal conductivity contrasts has not been analyzed. Refraction of heat is evident due to the extreme thermal conductivity contrast between the regolith (0.01 – 0.02 Wm-1K-1) and underlying basaltic rocks (0.5 – 1.0 Wm-1K-1). Outcrops of basalt peeking from beneath the regolith funnel the heat flow resulting in a decrease of the heat flow in low conductivity areas and an increase in high conductivity areas, respectively. The effect is enhanced by the topographic effect in craters, which become spots of very high heat flow. Two-dimensional (width 2.5 km, height 1.7 km) and three-dimensional (6 km x 5 km x 1.7 km) finite element models of conductive heat transfer indicate the commonly accepted value of 16 mWm-2 in the Taurus-Littrow site should be increased by about 3 mWm-2, i.e. by 19% to obtain an estimate representative for the valley floor at a depth where the topographic and refraction effects have attenuated (ca. 1.7 km depth). Our modeling illustrates the challenges in interpreting point-like lunar heat flow measurements and potentially contributes to planning of future thermal studies on the Moon, Mercury and Mars.