In Peter the Great's time the panels beneath the second-storey windows above the Main Staircase were decorated using grisaille painting - shades of a single colour. Experimental cleaning performed in 1973 revealed fragments of painting on four panels. Clearest among them are depictions of Vulcan and Neptune. It is possible that part of the painting was devoted to the then-fashionable allegorical theme of the four elements - Water (Neptune), Fire (Vulcan), Earth and Air - in the same way as the paintings on the coving of the central hall at Monplaisir in Peterhof. Today the paintings have been reinforced and conserved.