Multi-wavelength emission in Cygnus X. Top left: location of massive stars and star clusters shown overlaid on LOFAR 148 MHz continuum emission. Small green stars represent massive OB stars of the Cyg OB2 association and within the field (Berlanas et al. 2018), and small blue stars mark the locations of supergiants (Comerón et al. 2020). The gray circle represents the core of Cyg OB2 as identified by Wright et al. (2015). Large green stars mark the location of (open) clusters in the region (Le Duigou & Knodlseder 2002). Numbers in black text denote the position of radio continuum sources as identified by Downes & Rinehart (1966), and filamentary structures identified by Wendker et al. (1991) are designated with their CXR number. Top right: 1.4 GHz continuum emission observed through the CGPS (Taylor et al. 2003) and smoothed to a common resolution of 2′. Contours from the LOFAR 148 MHz continuum are overlaid at [10^−0,6,10^−0,55,10^−0.5…10°] Jy beairr⁻¹. The morphology in the majority of extended features is consistent with thermal continuum from low-density ionized gas and where relative differences in the intensity of the emission indicate free-free optical depth effects. Bottom left: MIR emission. In blue we show Spitzer 3.6 µm emission tracing the stellar population, in green the MSX 8 µm emission primarily from PAHs heated by UV radiation from massive stars tracing the PDR surfaces, and in red Spitzer 24 µm emission of warm dust, corresponding well with the diffuse ionized gas observed at 148 MHz. Bottom right: ¹³CO (1−0) integrated intensity observed with FCRAO (Schneider et al. 2007) tracing the bulk of the molecular gas with densities ≳3000 cm⁻³.