Cassini/ISS imagery and Cassini/VIMS spectral imaging observations from 0.35 to 5.12 μm show that Saturn’s north polar region (70°–90° N) evolved significantly between 2012 and 2017, with the region poleward of the hexagon changing from dark blue/green to a moderately brighter gold color, except for the inner eye region (88.2°–90° N), which remained relatively unchanged. These and even more dramatic near-IR changes can be reproduced by an aerosol model of four compact layers consisting of a stratospheric haze at an effective pressure near 50 mbar, a deeper haze of putative diphosphine particles typically near 300 mbar, an ammonia cloud layer with a base pressure between 0.4 bar and 1.3 bar, and a deeper cloud of a possible mix of NH4SH and water ice particles within the 2.7 to 4.5 bar region. Between the eye and the hexagon boundary near 75° N were many small discrete bright cloud features that VIMS spectra indicate have increased opacity in the ammonia cloud layer. Our analysis of the background clouds between the discrete features shows that between 2013 and 2016 the effective pressures of most layers changed very little, except for the ammonia ice layer, which decreased from about 1 bar to 0.4 bar near the edge of the eye, but increased to 1 bar inside the eye. Inside the hexagon there were large increases in optical depth, by up to a factor of 10 near the eye for the putative diphosphine layer and by a factor of four over most of the hexagon interior. Inside the eye, aerosol optical depths were very low, suggesting downwelling motions. The high contrast between eye and surroundings in 2016 was due to substantial increases in optical depths outside the eye. The color change from blue/green to gold inside most of the hexagon region can be explained in our model almost entirely by changes in the stratospheric haze, which increased between 2013 and 2016 by a factor of four in optical depth and by almost a factor of three in the short-wavelength peak of its wavelength-dependent imaginary index. A plausible mechanism for increasing aerosol opacity with time is the action of photochemistry as the north polar region became increasingly exposed to solar UV radiation. For 2013 we found an ammonia mixing ratio of about 50×10−6 in the depleted region between 4 bars and the NH3 condensation level (∼ 1 bar), but the NH3 results for 2016 are unclear due to very high retrieval uncertainties associated with increased aerosol opacity. We retrieved a deep abundance of about 5×10−6 for PH3 and a pressure breakpoint (where the PH3 abundance begins to decline with altitude) that coincided with the main cloud top near 300 mbar, except when that cloud opacity was very low, at which point the PH3 breakpoint pressure generally increased substantially, consistent with prior suggestions that the cloud layers shield PH3 from destruction by UV radiation above the clouds. We found an average AsH3 mixing ratio of 2×10−9 with some evidence for a decline with altitude above the main cloud layer. •From 2012 to 2017 Saturn’s north polar region changed color from blue/green to gold.•We analyzed Cassini/VIMS spectral imaging at wavelengths from 0.35 to 5.15 microns.•We used a compact 4-layer model with distinct compositions to model the evolution.•Stratospheric haze increases in opacity(X4) and absorption(X3) fit the color change.•Larger near-IR changes arise from 10X increases in opacity of a putative P2H4 layer.