The Countess of Wessex dropped in to officially open Sage House, the UK's first dementia hub located in Tangmere.
Her Royal Highness was welcomed by dignitaries before she met staff and volunteers of charity Dementia Support as well as people living with dementia, their families and carers.
She took a tour of the £1.7m facility, which will be a base for a number of charities and NHS trusts, before eating lunch and then unveiling a plaque to officially open Sage House to the 5,500 people who are living with the condition in the area.
The Countess was accompanied by Sally Tabbner and Anthony Wickins, Dementia Support chief executive and chairman and founder respectively, who showed her around the memory assessment zone, the daycare and activities zone and then onto the community cafe.
Ahead of the unveiling, Mr Wickins said: "Your Royal Highness, it's my privilege on behalf of Dementia Support to thank you for agreeing to officially open Sage House today, the first UK dementia support hub.
"Our vision is a society where dementia is wholly understood and accepted, enabling people living with dementia to be fully supported throughout their own journey.
"It is predicted that one million people in our country will be affected by dementia by 2025.
"The service we are providing here creates a one-stop-shop for people living with dementia and importantly their families and carers."
He added: "I hope you'll come to believe, as we do, that dementia support hubs become a nationally recognised model for supporting people whose lives are affected by dementia."
Before declaring the new facility open, Her Royal Highness said: "Thank you for inviting me today, I'm really pleased to be here to see the work you've put into it.
"Clearly it's going to serve your communities so very well and as you say provide the framework for models elsewhere in the country.
"On behalf of the individuals and families you are here to serve, thank you and all of your colleagues and associates for what you have done, I wish you every great success."
Iris Randell, 12, then presented her with a Dementia Support bracelet, before the Countess was given a posy by Edward, nine, and sister Bella Page, seven, who chose the name 'Daisy's Cafe' in honour of their great-grandmother for the community cafe.