The Italian city of Siena closed museums, schools and universities Thursday after a series of small earthquakes shook the famous Tuscan tourist destination.

A 3.5 magnitude tremor struck shortly before 2100 GMT Wednesday but no immediate damage was reported.

That was followed by some 20 smaller tremors overnight, according to Italy's National Institute of Geophysics and Volcanology (INGV).

Siena's city council said Thursday that Mayor Luigi De Mossi closed "the city's schools and museums... as well as the universities".

The southern Tuscan city is famous for its artistic heritage and for the Palio, a spectacular horse race that pits neighbourhoods against each other twice a year, on July 2 and August 16.

Its historic centre is listed as a World Heritage Site by UNESCO.

Italy is prone to earthquakes. Deadly quakes in 2009 and 2016 killed approximately 300 people each.