Tour de l'Isle, Medieval tower in Grenoble, France.

Tour de l'Isle is a square tower of pale beige stone standing beside a lower stone wall in Grenoble. Its sides measure 12 by 9.5 metres and it rises 23 metres over four floors, with walls more than 2 metres thick at ground level and 1.8 metres on the first floor. Small rectangular windows, some in pairs, pierce the flat faces, and a shallow hipped roof of terracotta tiles projects over a band of closely spaced stone brackets.

Construction of the square tower began around 1381 at the end of the 13th-century eastern extension of the Roman city wall, and the shell was finished by late 1390. The consuls of Grenoble commissioned it to strengthen the enceinte, and it housed the first town hall for two centuries. In 1590 Lesdiguières took the city, expelled the consuls and had the tower incorporated into a fortress; the last council meeting there was on 2 January 1591.

The tower's name comes from its setting beside the Isère and the Verderet stream, which then flowed into the river and made the spot seem insular. Four consuls in crimson velvet robes with yellow and red hoods met here every Friday, consulting a huge book chained to the wall that held the charters granted by the bishops and the Dauphins.

The tower stands on the banks of the Isère, and since 1994 a glass-and-steel footbridge links it to the Museum of Grenoble, whose exhibitions occupy its four levels. Entry follows the museum's conditions, so check its opening arrangements before setting out.

From 1887 to 1954 the tower housed a pigeon-fancying centre holding up to 300 birds, when the Vinoy barracks of the 140th infantry regiment stood on the site. The barracks was demolished in the 1970s, leaving a car park, and since 1994 a glass-and-steel footbridge has linked the tower to the Grenoble museum.