Samuel Guerrero: Sol Roto

A chromed metal strip on the Kunsthalle's back wall marks where the sun's shadow falls on Chinese New Year. Five more do the same for the Jewish, Gregorian, Persian, Indian and Islamic new years, so one wall keeps six calendars.

Samuel Guerrero has turned the 33-metre wall into a sundial that runs for a year. Metal sculptures register the solstices and equinoxes, reflective surfaces redirect sunlight across it, the sun's heat is turned into sound, and 365 metal leaves play against the shadows of the nearby trees. Engraved plaques add four moments in history, among them Basel Time, the local clock that ran an hour ahead of standard time for 400 years, until 1798. So arriving early here is, technically, heritage.

You see it from outside: it is a public-space commission, so there is no ticket. The work changes with the seasons, and its calendar marks the winter solstice on 21 December, Chinese New Year on 6 February and a solar eclipse on 2 August 2027, before it closes.