Events were held around Wales on Thursday to mark the monarch's milestone birthday, including a 21-gun salute and fireworks at Cardiff Castle.
The Queen was in Windsor to light the first of more than 900 beacons in the UK and around the world.
Army Cadets lit the Snowdon one while others were lit in Swansea, Wrexham, Llantrisant and Cardiff Bay.
The 21-gun salute was sounded at 12:00 BST and there was a drinks reception for other people celebrating milestone birthdays and anniversaries.
"This is a wonderful opportunity for people to come together and commemorate their special milestones with that of Her Majesty," said Cardiff Lord Mayor, David Walker.
Meanwhile, 40 giant fibreglass models of the Queen's head are being displayed at a farm in Flintshire.
David Pickering won lottery funding to create them for the Diamond Jubilee in 2012.
He has decided to display them again on his land near Higher Kinnerton as the nation pays tribute to Britain's longest-serving monarch.
A beacon has been lit at the top of Snowdon as part of festivities to celebrate the Queen's 90th birthday.