Update - 3.54pm: Demonstrators at today’s Take Back the City march have held a sit down protest on O’Connell Bridge in Dublin.
Organisers say it is to highlight the housing crisis which has become an emergency and needs urgent government action.
The Take Back The City demonstration started at around 1pm at the Garden of Remembrance before marching down O’Connell Street under garda escort.
The number of protesters increased to more than 1,000 later in the afternoon and many took part in a sit-down protest on O’Connell Street and O’Connell Bridge, bringing traffic to a standstill.
The Take Back The City movement has previously occupied vacant properties in Dublin in protest against the housing crisis.
The Dublin demonstration was one of a number taking place across Ireland.
We have every corner of O'Connell Street blocked off. Take Back the City by name, Take Back the City by nature ✊🏽 pic.twitter.com/XMJeV2QZOy— Take Back The City - Dublin (@TBTCDublin) September 22, 2018
Sinn Fein leader Mary-Lou McDonald was among those attending the protest.
Housing Minister Eoghan Murphy came under increased pressure during the summer as homeless figures threatened to hit 10,000.
Sinn Fein has submitted a motion of no confidence in Mr Murphy, which will be debated in the Dail next Tuesday.
Earlier this month, Gardai came under criticism after five housing protesters were arrested following the occupation of a house in Dublin’s North Frederick Street.
Update - 1.15pm: Housing protests are underway at 20 locations around the country including Cork, Waterford, Limerick, Sligo, Drogheda and Bray.
The largest demonstration being held at the Garden of Remembrance in Dublin.
The housing activist group, Take Back The City, is behind today's events. The organisers say the housing crisis is an 'island-wide' issue.
Organisers of today's demonstrations say they're calling on "grassroots groups, housing activists, and community groups nationwide" to take part.
Crowds starting to gather at the #TakeBackTheCity protest at the Garden of Remembrance in Dublin. Several protests are taking part across the country today as part of the National Day of Action pic.twitter.com/nfXHOUfbsv— Barry Whyte (@BarryWhyte85) September 22, 2018
Activists in Dublin say they have also occupied a vacant property in Crumlin to coincide with today's demonstrations.
People Before Profit TD Bríd Smith said: “Activists are challenging the idea that properties can lie vacant in the midst of a housing crisis.
"They recognise that the government’s commitment to the market is providing no real solutions."
Thousands of people are expected to take part in a national protest against the housing crisis today.
Today is your opportunity to get involved in #TakeBackTheCity
or not. pic.twitter.com/ABFsDdL2Tm— HomeSweetHome (@HSHIreland) September 22, 2018
Demonstrations are set to be held across 13 counties with the largest starting at Dublin's Garden of Remembrance at 1pm.
The latest figures from the Department of Housing show just under 10,000 people accessed emergency accommodation in July.
Aaron from Take Back the City says homelessness is an island-wide problem.
He said: I think the question of the housing crisis is somethong that's affecting all directly or indirectly and is the issue of the day for most Irish people.
"Day by day there is an ineptitude from the Government to solve this crisis and it's something that affects all of us."
PA & Digital Desk