Representatives from eight cities protested against the rules applicable to holiday letting platforms, advocating more transparent regulation. The municipalities of the cities of Barcelona, Madrid, Brussels, Paris, Krakow, Vienna, Reykjavik and Amsterdam subscribed to the declaration sent to the EU Commission. City officials stated that online tourist letting platforms such as Airbnb and Booking.com should be obliged to share data with regulators. Currently, these internet booking services permit the anonymity of listing owners of properties as well as of the holidaymakers who let them, exacerbating pressures that the recent invasion of mass tourism places on the infrastructure of these municipalities.