It isn't a secret for anybody that visual aspects are a big focus in design: the volumetric composition, the views from the building, the materiality of the facade. But what happens with smell? Is it a "lesser" sense compared to sight?
Based on my experience in the architecture field so far, my perception is that the olfactory is underestimated; it is mainly conceived as a problematic area we have to deal with inside the design process. When designing a restaurant, a residence or a hospital the focus is towards the mechanical ventilation systems to prevent bad odors, instead of offering elements for delight.
In like manner, urban planner and academic Victoria Henshaw argues in her book Urban Smellscapes (2013) that scent has been critically ignored in how we plan spaces. She claims the city has substituted the familiar metropolitan whiffs of previous ages with a desire to make places neutral, calling it a misplacement of our "smell-ability". 
But why do we fail to embrace the olfactory in our work as designers and city planners?
Despite the fact it has a huge influence on our perception of places, smell has been crucially overlooked by urban planners and scientists alike, not least because it is difficult to record and analyze at scale. 
Perhaps the way smell functions could be one of the causes of this sense being undervalued. We breathe in and out more than 20,000 times a day, and it is fundamental we have a filtering mechanism that allows our minds to switch off from the many smells in the air, otherwise, we would face constant distraction.
Besides the biological aspect, there is a conceptual misunderstanding of the participation of smell in the cities. Through history, cities have been portrayed as smelly and dirty places, where animal, human and industrial waste create a fog of unpleasant aromas. As a result, our notion of the olfactory has been affected, creating an incorrect idea that it is something with little to offer to our urban designs, which is far from the truth.
Science historian Diana Ackerman explores the subject of smell and its power in A Natural History of Senses, giving great recognition to the psycho-emotional and cognitive effect of the olfactory:
This direct connection is also what makes smell so potent, and at the same time, what gives smell enormous possibilities to create pleasure in today's metropolis. In times of globalization where everything seems to become homogeneous, the insertion of pleasant and diverse aromas can contribute to the personality of our cities.
Regarding this matter, Henshaw points out Japan as an example of what we could do towards the olfactory sense with the project called "One Hundred Sites of Good Fragrance", which is active across the country. From the sea mist of Kushiro to the Nanbu rice cracker of Morioka, and the distinct smell of glue around the doll craftsmen's homes in Koriyama, they all have protected status as a way to praise their national aromas. 
Other remarkable initiatives related to the power of smell have been made not only in urban contemporary approaches; the use of scents in conjunction with films dates back to 1906, even before the introduction of sound. For instance, the system "Smell-O-Vision" released odor during the projection of a film so that the viewer could smell what was happening in the movie, in this case, triggered by the film's soundtrack.
What's more, this idea has been making a comeback at film festivals like the Widescreen Weekend 2015 in Bradford, and AEG is now bringing effects like scent, smoke, and wind into 4D movie theaters in the US. 
Likewise, stores like Nike, Sony, and Abercrombie & Fitch have been using smells to boost brand identity, and if you have walked past a Subway restaurant you must have experienced how they use the smell of freshly baked bread to attract customers.
Even if I am not hungry, that smell is incredibly appealing.
These actions in the entertainment and retail sectors can serve as an inspiration to city planning and architecture, as ways to embrace environmental scents. Forms and materials play a fundamental role in smell ambiance, and if a scent is used strategically with other sensory elements it can help create very strong atmospheres.
One wonderful experience that could help us become more conscious of the role of smell in our environment is a "smell-walk", which is a walk focused on the discovery and appreciation of the fragrances around the city. This kind of activities are starting to take place in different places of the world, such as "Smells Like Wien Spirit" in Vienna: 
If there aren't any in your city, here is a free guide by artist and designer Kate McLean to do it by yourself!
Just think about what fresh flowers, the rich steam of coffee or the subtle smell of mountain air can do as elements of arousal to our organism. In the same way, a rich variety of odors in the city, linked with different forms, materials, and activities can enrich our metropolitan experience and truly stimulate our sensory imagination.
It is a special feeling to come across a scent that triggers a connection to our home, a person or a period of our life, and that holds huge value not only on an individual level, but it can also serve to shape spaces and impact community in a broader scale.
Instead of trying to create sterile ambiances, smell can be used as a powerful element of design by building memories, character and providing a sense of place.
(1) Henshaw, V. (2013) Urban Smellscapes: Understanding and Designing City Smell Environments. New York: Routledge.
(2) Aiello, L., et al. (2015) Smelly Maps: The Digital Life of Urban Smellscapes. Retrieved November 01, 2017 from: https://arxiv.org/abs/1505.06851
(3) Ackerman, D. (1990) A Natural History of the Senses. New York: Vintage Books.
(4) Robin. (2014) One Hundred Sites of Good Fragrance. Now Smell This. Retrieved November 01, 2017 from: http://www.nstperfume.com/2014/04/01/one-hundred-sites-of-good-fragrance/
(5) Duell, M. (2016) How we could soon all be watching Smell-O-Vision: Film festivals recreate 1960 concept as new virtual reality technology is release. MailOnline. Retrieved November 01, 2017 from: http://www.dailymail.co.uk/news/article-3334085/How-soon-watching-Smell-O-Vision-Film-festivals-recreate-1960-concept-new-virtual-reality-technology-released.html
(6) Space and Place. Smells Like Wien Spirit. Retrieved October 29, 2017 from: http://spaceandplace.at/SmellslikeWienSpirit