Located in the heart of Madrid, the Be Live City Center Madrid Santo Domingo Hotel (previously the Mercure Madrid Santo Domingo or just Hotel Santo Domingo) is a comfortable boutique 4 star hotel dedicated to artistic creation, designed to host all kinds of events and offer a full range of services. It boasts a rooftop pool, individually decorated themed rooms, a private art collection on its walls, various colorful mural frescoes painted by local artists in its car park, and a light show on its exterior façade, among numerous amenities.

The establishment occupies two buildings, one contemporary and one 16th century structure whose vaulted cellars once housed the Inquisition’s archives and is a work of art in itself. The proprietors decided to cover the barren interior courtyard walls since 70 out of its 200 rooms overlooked the bare space, but it was a challenge to create original, spectacular and stunning views for this Madrid city center hotel. In line with the hotel owners’ artistic and ecological aesthetic, along with a desire to provide differentiation and added value to its customers, a spectacular living vertical garden was desired. And they desired a true soil-based “hanging garden” that patrons could walk under to appreciate, as opposed to a hydroponic greenwall.

Completed in June, 2011 the beautiful inner courtyard showcases the world’s largest hanging garden (according to Guinness World Records as of November 23, 2011): an immense 1,026 m2 wall of greenery (including the vegetated terraced areas, 844 m² without) made up of over 260 species of trees, shrubs, climbing plants and herbs with an impressive 20 meter high waterfall. Inspired by the Hanging Gardens of Babylon, the 22.9 meter high greenwall is one of the hotel’s masterpieces and now over a third of the hotel’s guest rooms look directly out onto its hanging garden and spectacular night lighting.

Upon arrival to their rooms, the surprised and delighted guests are greeted with an informative brochure describing the many environmentally friendly features of the hanging garden. After returning from a long day of work, shopping, or sightseeing, guests can relax in the green oasis-like atmosphere.

Designed by architect Félix González Vela, the project necessitated a complex structure, hidden from view by the flora and vegetation of the greenwall. With an investment of more than 480,000 euros, a team of more than 15 technicians of various specialties created the Hanging Gardens using 300 linear meters of scaffolding. Along with hotel maintenance staff, Heather meshes were placed to hide the scaffolding. This system has the advantage of accessibility for maintenance, avoiding the use of cranes and climbing techniques.

In total, more than 2,500 varieties of plants and flowers, highlighting seasonal species, non-allergenic shrubs and trees were used in 400 staggered planters of different sizes with about 40,000 liters of specially designed growing media. Eight trees reach about about 5 meters high and there are many smaller shrubs, about 30, plus vines, and herbaceous perennials and seasonal flowering plants, ensuring colorful year round vegetation. The drip irrigation system is fully automated to achieve the maximum benefit with minimum expenditure of water. Nutrients and moisture are kept constant throughout the day, depending on the humidity detected in different irrigation control probes. The plants are changed twice a year as necessary; three annual fertilization applications of 0.5% guano are performed and monitored with biological control of pests.

Among the species we can find begonia, pine, cypress, eucalyptus, boxwood, laurel, Mexican blue palm, palm of the church, prunos, ivy, rustifinas, dahlias, Tree of Jupiter, impatiens, brassicas, cold jasmine, etc. Plants are arranged along the garden according to agronomic and ornamental criteria, choosing species suitable for shady areas, and areas highly exposed to wind and sun.

In addition to its beauty, the green architecture project offers many advantages to the environment. Given the large number of plants, the garden promotes biodiversity and small nesting birds are welcome. In fact, several pairs of blackbirds have chosen the Hanging Garden of the Hotel Santo Domingo for their home and are the first “winged hotel guests.” Considering the large volume and coverage of the foliage, the greenwall also helps in acoustic insulation, considering that most species are evergreen. The vertical garden is also estimated to absorb 25,000 kg of CO2 per year, and its comparatively high oxygen production supplies enough oxygen for about 200 people a day.

A particular highlight of the project is the spectacular artificial waterfall 20 meters high that descends from the top of the garden, providing a point of exoticism and freshness. Its role is crucial for the maintenance of the plants and the reduction of the temperature of the garden. Starting 5 meters over the Natura Lounge in the Lobby, it allows visitors to sit under it just below the base where water is collected and patrons can see the water breaking against the glass shelf just above their heads. It has thirty outlets with different types of water jets and four levels of output for the waterfall, allowing multiple design possibilities using a software program. It also has six programs for different sets of light and sound to create atmospheres and environments for customers to enjoy.

The recycled irrigation flow is 3,000 liters/hour. The hotel says the waterfall also minimizes the heat island effect, and that it can reduce the temperature between the inside and outside of the city between 4 and 6 degrees, equivalent to 50 air conditioners but without the harmful emissions. After a process of settling, purification and chlorination from the graywater collection of showers and sinks from 50 rooms, the water is reused for the toilets in each room as well as the waterfall.

The hanging garden also has an advanced system of night lighting technology with LEDs that delight guests and visitors, offering a show of varying colors during day and nighttime.

One of the most important economic aspects of the Hotel Santo Domingo Hanging Garden is the maintenance cost. For a garden area of this complexity, the cost is about 350 euros per month, excluding seasonal flower changes. The amount is much lower than the cost of maintenance of other vertical gardens. The reasons are the use of gardening techniques, reuse, and access to maintenance tasks.