La Nef solaire, Monumental sundial sculpture at A9 motorway rest area in Tavel, France

La Nef solaire is a monumental sundial made of steel and concrete located at the Tavel Nord rest area along the A9 motorway. The structure consists of two intersecting pyramid-shaped forms that function as both a working timepiece and an artistic installation.

The work was created in 1993 through a collaboration between sculptor Odile Mir, astronomer Denis Savoie, and engineer Robert Queudot. This partnership united artistic vision with scientific precision and technical expertise.

The work is a working sundial: it shows solar time, and visitors must convert it according to the CET or CEST time zone to get legal clock time. Its three authors — sculptor Odile Mir, astronomer Denis Savoie and engineer Robert Queudot — combined sculpture with astronomical calculation, and the piece is often cited as an example of so-called "highway art".

You can visit the work free of charge during a stop at the Tavel Nord rest area. Keep in mind that the displayed time requires conversion from solar time to Central European Time to determine the actual clock time.

The dial shows true solar time, so it runs ahead of or behind clock time depending on the season and on whether France is on CET or CEST; a conversion is needed to read legal time. The work is often cited as an example of the pejorative label "highway art".