It was possibly the worst kept secret in Dublin commercial property circles.

For months rumours and reports have abounded that Facebook was getting close to sealing the deal on a lease on the Bank Centre campus in Ballsbridge.

But nonetheless, the news that the agreement has been formalised was nonetheless interesting.

Facebook has agreed terms to take over control of the entire 14-acre site that was once dominated by AIB for several decades.

The bank, which has gradually reduced its occupation of the campus in recent years as staff numbers fell, will leave it completely in the coming months for pastures new.

The social network will then do some renovations to the existing AIB bank headquarters before starting to move people in there.

More extensive renovations will be carried out to the other older blocks and an entirely new building will also be constructed.

As a result, Facebook’s movement into the site will be staggered over the next three or so years and all 2,000 of its existing permanent staff will not have made the move until 2022.

The company will still retain its Beckett Building in East Wall where many of its other outsourced staff and contractors are and will remain based.

It also has an office in Cork where part of its Oculus VR system is developed and a massive expanding data centre in Clonee, Co Meath.

Gareth Lambe, Head of Facebook in Ireland, wouldn’t say precisely how much the Ballsbridge investment was worth, but did say over an extended period of time it would be worth hundreds of millions of euro.

It’s a deal that has been something of a labour of love for the country boss and his internal and external team, who said he was proud that Facebook was committing itself to Ireland in such a way.

The Ballsbridge project has taken a long time because of the ownership structure of the bank centre properties.

A number of the blocks are the property of the Serpentine Constortium – a syndicate assembled by Goodbody Stockbrokers and AIB Private Bank.

More still are owned by Davy Target Investments and the rest by Johnny Ronan’s Ronan Group Real Estate.

That’s a lot of ducks to get in a row and it is this challenge that Facebook’s staff and agents have been working on over the past year.

Facebook has taken a bashing on a number of fronts in recent times around its commitment to trust, safety and privacy issues, not least here in Ireland

But this investment is a clear signal that one thing it is committed to is a future of scale and growth in Ireland.

Here since 2008, Facebook already employs 4,000 people in total in Ireland in engineering, sales, support, legal, finance, safety and many other roles across 60 teams.

Lambe’s vision is of a self-contained Facebook campus for the company’s operations here, smaller but not unlike its headquarters in Menlo Park in California.

"We're very excited about the campus project which will provide our employees and partners a state-of-the-art, modern work environment with lots of collaborative spaces, training spaces and an outdoor plaza with seating areas," he said.

Facebook recently opened a new building in Menlo Park, which may provide something of an insight into what the revamped Bank Centre campus will be like.

According to reports, the snappily named "MPK21" was designed to resemble a village, with a "main street", "neighbourhoods" , "town square" complete with redwoods and a botanical garden area called "The Bowl".

The idea of all this, of course, is to continue to attract the best talent possible to help propel the growth of the firm.

And grow it will, with space in the campus when it is finished for 5,000 more employees on top of the 2,000 who will migrate from its European Headquarters in Grand Canal Square.

Indeed, the company does not intend to lease any of the space in the new campus.

So while it isn’t making any firm commitments today on adding jobs, it seems likely that its employment growth trajectory will be exponential in the coming years.

It all comes at a pivotal time for the firm though.

Its last set of earnings published at the end of October were something of a mixed bag.

Revenue was up, but not by as much as had been expected.

User growth was also shown to be slowing, with tighter privacy rules in Europe and less interest in the platform among teenagers taking a toll.

The firm also admitted that Facebook, Instagram, WhatsApp and Oculus also face increasing competition from other big players in the market.

The company is also continuing to grapple with the fallout from recent scandals, by investing in technology, people and procedures, all with the aim of stopping election interference, improving user data privacy and protecting those who use the platform.

Mark Zuckerberg said last month that investment would continue into 2019 and it is now clear from today’s announcement that Ireland is central to those plans.

But it does all raise interesting questions about just what Facebook as a company will look like in three years time when the final employees leave their desks in Grand Canal Square for their new village in Ballsbridge.

Comments welcome via Twitter to @willgoodbody