Watford Borough Council took part in a national campaign led by NHS England.
Watford Town Hall was lit up in blue on Thursday 5 July as Watford Borough Council joined organisations up and down the country to celebrate 70 years of the NHS.
Other landmark buildings that were lit up in blue included Blackpool Tower, the Gateshead Millennium Bridge, Manchester Town Hall and the Leeds First Direct Arena.
The lights outside of Watford Town Hall were turned on at 6pm on Thursday.
Elected Mayor of Watford Peter Taylor said: “We are very proud of the NHS, and happy to support it in any way we can. We are very proud of all the doctors, nurses, staff and volunteers who work at Watford General Hospital and our local healthcare centres. They work very hard, and we would like to take this opportunity to say thank you to all of them.”