Some 50 countries across Europe take part in the annual event, which allows members of the public free access to some of each country's most important cultural sites.
This year's theme is ‘Power and splendour' and explores how power manifests itself in buildings and intangible cultural heritage.
Nearly 1,000 events are being held in 330 locations across Switzerland, including guided tours, children's workshops, debates and walks.
Participating buildings include the Swiss Federal Court at Mon Repos in Lausanne, the former Maggi factor in Kemptthal, the French ambassador's villa in Bern and Rapperswil castle.
For the full programme and details of how to book, visit venezvisiter.ch