Modern Frank Lloyd Wright in the majority of his

Modern space draws an ambiguous line between inside and outside, a feature that becomes recognised as one of the most fundamental elements of modernist architecture. By exploring this new spatial quality, architects can create places that exhibit different ambiences that complement the design, drawing out distinct user experiences. When one designs a space, the relationship between the inside and outside is ever-present, since architecture not only provides shelter from the nature of the surroundings but simultaneously creates an interior. Yet this relationship is not only achieved by a singular method, thus allowing architects to provide spatial experience whilst defining the space with their personal perception, projecting their stance in the architecture, with some even utilising this as a design component. For example, Frank Lloyd Wright and Mies van der Rohe can be said to have used this relationship particularly effectively.
One method that expresses the spatial relationship is through referring to the landscape in which the building stands on and projects from, allowing both the building and environment to coexist with each other, enhancing the experience with fluid movement. This approach was successfully done by Frank Lloyd Wright in the majority of his buildings allowing individuals to personally relate to space by experiencing the spatial quality as a journey through the dwelling. This special unification of the interior and exterior allowed his architecture to feel consistent, complete but also private. The start of this perception of space had begun when he opened the pages of ‘The Book of Tea’ written by Okakura Kakuzo, with a quote from the great Chinese poet-prophet Lao-tzu stating that “The reality of the building does not consist of four walls and the roof but in the space within to be lived in.” (1955, p. 80) granting him the establishment of a new take on the concept of interior space with a mind of “dismembering the traditional box.” (Brooks, 1981, p. 176) For the ‘traditional box’ had been the buildings that imprisoned rather than opened to the surroundings with unconstrained views. For example, the Unity Temple appears to have less enclosing walls, replaced with other components such as screens freeing the space allowing what Kaufmann (1955, p. 75) describes as “the interior space opening to the outside and see the outside coming in” to happen.
Frank Lloyd Wright had also believed that spaces were perceived by people and so the experiences they receive vary, dictated by the movement of individuals through the building. This leaves different views of a building to be regarded. Brooks (1981, p. 177) stated that “In Wright’s work, space loses its fixed value and acquires a relative one” due to it relating to “individuals and their changing position within the space.” This results in hidden elements of space that gets revealed with movement, allowing a sense of mystery and surprise to occur, playing with the emotions of the user while the user brings a metaphor of the exterior inside. The previous theory is enhanced by having spaces that coexist and overlap, weaving the exterior and interior together so that each element integrates to create a whole experience. If we study the plans of Robie House (fig.), Frank Lloyd Wright has incorporated the dining and living room together allowing them to become one without a loss of privacy. It creates hallways of spaces that flow into each room, expanding the spaciousness with adjoining windows, parallel to the planes of landscape directly outside. The overlapping of planes allows the harmony between the inside and outside to occur, yet bringing a sense of enclosure to the room, ensuring privacy. 
Defining the role of an architect as a mechanism that helps others realise and understand the elements of life which make it more beautiful. Wright had strongly believed that the creation of a good building gives new purpose to life, presenting harmony and moral in the existence of people. To establish communities that flow through architecture, Wright understood that space and structure could be used as persuasive design components to convey such meaning, which he then produced powerful new forms to manifest his vision of the change. His need to produce a whole environment that coexists with the landscape, whilst honouring the human scale, builds a bridge to nature and allows his buildings to parade warmth, continuity and the marriage of space developing complex relationships. Wright’s spaces had interior forms which symbolise the external spaces and vice versa with exteriors that “usually project internal spaces” (MacCormac, 1981, p. 167), forming a union of space and nature. The Willits House entrance (fig.) is an example of this expression which includes being covered by a hipped roof and enclosed by walls allowing the experience of being “virtually inside without yet going through a door.” (Heinz, 1992, p. 11) The projection of his beliefs made his buildings effective in showing the altering spaces of the inside and outside, enhancing the exterior by framing the landscape to the desired view and exploring a view that was never seen before. While the interior is freed from the ‘traditional box’, opening to the outside projecting Wright’s opinion that “the good building is not one that hurts the landscape, but one which makes the landscape more beautiful than it was before the building was built.” (Hertzberg, 2004, p. 11) 
Similarly, Mies van der Rohe joins the spaces together so that the separation of the inside and outside spaces encounters no disengagement, however, he finds the solution in relying on the walls less and instead using a few partitions as building components. With an extensive amount of glass in his designs, exposing the building, it combines the interior and exterior with a fluid transition of space. He uses this transitional space to project his theory of “Less is more” (Schulze and Windhorst, 1989, p. 205) allowing him to reach a level of simplicity and transparency that had not existed before. His buildings constructed with a steel structure and glass façade are referred to as ‘skin-and-bones’ architecture for the visual similarity of the construction to the body. The Esters and Hermann Lange Houses show this well as “the wall is pierced in both houses by a window, allowing morning light to filter through and enhancing the sense of the brick walls as a thin skin.” (Riley and Bergdoll, 2003, p. 89) During that period, glass became a strong base for the modernist movement as it redefined space with its new material properties. The use of glass to replace walls in his work allowed the inside and outside spaces to coexist creating spaces that allowed for continuity, framing the views of the outer surroundings along the way. The glass captures the surroundings, reflecting the landscape back inside, granting a desirable but filtered and restricted view of the place. The use of glass played a big role in helping him free the plan allowing broad, open spaces to be freely designed, connecting humans back to nature, highlighting his need to unify human, nature and architecture whilst blurring the divisions between interior and exterior.
The ‘Villa Tugendhat’ was a clear approach of these spaces projecting his beliefs on architecture within the design. By using an iron framework, he could easily erase the load bearing walls opening the building to a more spacious and light-filled zone. Replacing the walls located on the second floor with windows that descend all the way from the ceiling to the floor in the southeast and garden facades, the room is used as living space and due to the transparency, the space spreads to the outside leading Riley and Bergdoll (2003, p. 242) to describe that the “living area is thus simultaneously interior and exterior.” With a winter garden located on the east side, it captures an exterior panorama within architectural confines, extending to meet the original landscape of nature. These actions indicate his portrayal of space, that “Instead of forming a closed volume, these independent walls, joined only by planes of glass, create a new ambiguous sensation of space. Indoors and outdoors are no longer easily defined; they flow into each other.” (Russell, 1986, pp. 16-17) Despite the exposure that comes with glass, the villa respects the privacy of the residents with screens that shield the bedrooms from the outside, contrasting with the second floor, giving his take on wanting to create spaces that gave a sense of enclosure whilst also gifting the end-user with perspectives of the land and sky. Another element present in his work were transitional spaces connecting the indoors to the outdoors, this allowed the flow of space to be bounded whilst changing the environment and atmosphere to heighten the sense of space. Taking advantage of light, he uses it as a choreography to guide the consumers into the building, slowly drawing them into a series of transitional spaces without taking out the interest of the building. The plan of ‘Villa Tugendhat’ (fig.) shows this with the stairs leading up to the bottom terrace and through the interior with the planes of glass that reflect to the garden, navigating all the way to another terrace allowing what Frohburg (2015, p. 198) declares as a “seamless visual transitions from interior to exterior space” to happen. 
Both Mies van der Rohe and Frank Lloyd Wright took up a liking of designing furniture for dwellings, even assigning them into designated areas where they thought suited the scheme the most. In the later works of Mies, sculptures even had precise placements located outdoors in ways that connected the exterior back to the interior, “heightening its impression of space.” (Krohn, 2014, p. 23) His need to have a complete building filled with fixed furniture relates to his want for the exterior to project meaning as a whole component, for to produce buildings that show the very minimal but in fact, is planned from every detail is the essence in his designs. The Farnsworth House is an ideal building that shows this belief with Krohn (2014, p. 146) stating that “When you see nature through the glass walls of the Farnsworth House, it gets a deeper meaning than outside. More is asked for from nature because it becomes a part of a larger whole.” He even went to the widths of using more neutral colours on the inside as the exterior had an exceptional view of the colourful trees that circle the house, showing that he had a strong desire to expose the views of nature from the inside, stating that “We need do nothing, but eliminate the barrier between interior and exterior” (Co, 1990, pp. 288-291).     
By using similar ideas yet producing buildings that vary from appearance to the atmosphere was due to the ideas being used in different methods, achieving different spatial qualities because their beliefs and driving force of design are different and personal, projecting their stance in architecture. For built architecture is a visual manifesto of their views. From using spaces that combine the inside and outside, it creates a strong element in the building refining user experience whilst also portraying their opinions visually. Wright had used this opportunity to merge spaces together creating unity but not forgetting privacy, adjusting his buildings to create an even better view of the site allowing consumers to discover the beauty of the landscape that was not noticed before. The use of cantilevers and horizontal planes allow the user to experience the interior even before they reach the inside, foreshadowing the sense of space that has yet to come. On the other hand, Mies van der Rohe dissolved the boundary of the interior and exterior spaces using glass as a tool to provide openness, allowing inhabitants to be constantly surrounded by views as if the room had already become one with nature. Likewise, both focused on architecture as a whole – inside and outside, to produce the perfect vision of space with the site as a unity that enraptures users to nature and architecture concurrently.