Large-scale structure of the cold neutral medium (CNM) measured as HISA in the THOR survey (top panel, Beuther et al. 2016; Wang et al. 2020a,b) and the ¹³CO(1–0) emission from GRS (bottom panel, Jackson et al. 2006). The color scales show the inverted HISA emission and ¹³CO(1–0) maps, respectively (integrated from 71 to 86 km s⁻¹ above 15 K in the HISA spectrum), and the contours show the 875 μm emission from the ATLASGAL survey (Schuller et al. 2009, contour levels start at the 4σ level of 200 mJy beam⁻¹ and continuein 8σ steps up to 1.8 Jy beam⁻¹). The white box outlines the approximate region imaged with APEX in the [CI] and ¹³CO(3–2) emission. A scale bar is shown within the box.