This December, a Real Madrid-themed winter wonderland has taken over the Bernabeu.

The club are calling it Mavidad (navidad is Spanish for Christmas). A giant slide now stretches from the stands to the playing surface, where an ice rink, stalls and hot chocolate stands are where the pitch would be.

It is another example of how Madrid are looking to increase stadium-related revenue at their redesigned home ground.

Back in November, the NFL came to the Bernabeu. Artists such as Taylor Swift have held concerts there, although these have been suspended after legal action from nearby residents who complained about the noise.

Madrid’s idea is to boost their finances and help repay the costs of the iconic ground’s renovation. They have already invested €1.3bn (£1.1bn; $1.6bn) in the refurbishment — with around 87 per cent of that money borrowed.

In 2024-25, Madrid’s stadium revenues totalled €326million (£284m; $383m), an “enormous” figure according to The Athletic’s football finance expert Chris Weatherspoon, and one which the club still believes is well short of the Bernabeu’s potential. Events and concerts generated €15.4m — but none were allowed after September 2024.

If there is one secret to bringing Madrid’s plan all together, it is the remarkable technology hidden underneath the stadium.

Mavidad will shut later today. By Saturday, the Christmas trees will be gone and the pitch will have been brought back into place, emerging from below via a complex system of conveyor belts. On Sunday, Xabi Alonso’s side welcome Real Betis as La Liga resumes from its winter break.

How does it all work?

Underneath Madrid’s ground lies a cavernous and intricate piece of engineering described as the world’s first by those involved in its design and construction.

Real Madrid insiders refer to it by a nickname: el hipogeo — the hypogeum — a term that typically describes elaborate subterranean burial places from the ancient world.

Madrid’s version runs about 25 metres deep underneath the Bernabeu, along the west side of the ground.

Jorge Vizcaya, an architect at SENER, the company that carried out the project, says it comes close to an underground railway line that “practically skirts the north-east corner of the stadium”. He adds: “It would only take a deviation of one centimetre to touch the train tunnel.”

The pitch is divided into six sections, 11.67m wide and 107m long. When they need to be replaced, a remarkable piece of engineering means they can essentially be neatly folded down into the depths. It allows Madrid to quickly and efficiently change their playing surface, or swap it out for an alternative.

The pitch replacement system was a key part of the Bernabeu redesign (Real Madrid)

Down there, more remarkable things happen. The ‘hypogeum’ is essentially an enormous greenhouse, although one entirely devoid of natural sunlight.

According to Madrid, sources familiar with the system — who, like others consulted for this article, preferred to speak anonymously as they did not have permission to comment — the height of the Bernabeu’s stands (about 60m) would make it difficult to fully rely on natural sunlight to help keep the grass of the pitch in perfect condition. Now it is treated with grow lamps, up on the surface and down below, where backup pitches are prepared for later use.

These same sources also explain that Madrid took inspiration from scientific studies on cannabis cultivation to help design their underground grow house, as they were among the few available on indoor grass cultivation.

Vinicius Junior running at Sevilla defender Juanlu Sanchez on December 20 (Alberto Gardin/NurPhoto via Getty Images)

During its first season in operation, over 2023-24, there were issues with the Bernabeu pitch. It was common for the turf to be in less-than-perfect condition.

Now, the situation is considered to be more settled, although improvements continue to be made. Usually, the turf is replaced before the start of the season and, if necessary, again during the campaign. When Madrid hosted Sevilla on December 20, they did so with a newly installed turf.

The process of changing the turf usually takes around two days (three at most) and consists of removing the field, installing the new drainage system and laying the grass. Any turf that is stored below the pitch is monitored carefully to make sure that conditions are correct.

There is a team of approximately 70 people, including full-time and part-time staff, with responsibilities for maintaining and improving the various pitches at Real Madrid. In total, they have 13 natural turf pitches across the Bernabeu and the training ground.

Madrid also have a laboratory in their training complex, where experiments on improvements to the condition of the grass can be conducted, involving tests with different types of seeds, equipment and treatments.

Due to European and Spanish regulations, which are stricter than those in England or the U.S., the club follows environmentally friendly conservation methods. For example, fungi that are harmful to the grass are not killed with pesticides, but with ultraviolet light.

The condition of the grass is also carefully checked to ensure conditions are suitable to try and prevent injuries.

For some time, there has been speculation that the Bernabeu’s turf was painted. The rumours reached the club, where some employees even asked if this was the case, but according to knowledgeable sources, it is not true.

To build their huge underground greenhouse, Madrid requested a loan of €225million, to be repaid at an interest rate of 1.53 per cent, which the club considered advantageous. Sources at SENER say their system was not as expensive as the amount requested in that second loan, but added that costs reflected the nature of building around an existing structure.

In total, Madrid arranged three loans totalling €1.17billion of debt for the Bernabeu refurbishment, with an average interest rate of 3.2 per cent.

The other two loans were for €575million (at an interest rate of 2.5 per cent), mainly for the stadium’s exterior structure and retractable roof, and €370m (at an undisclosed interest rate) to cover cost overruns.

At Madrid’s ordinary general meeting of members in November, the club president, Florentino Perez, said the investment made so far was €1.347 billion, but he did not specify whether that could increase due to further works, such as the soundproofing the stadium must now have.

But the big idea is that the boost in revenue Madrid hope to bring in through keeping the Bernabeu operational year-round will contribute to covering those costs — and over time further help the club’s financial picture.