It can be defined by trees and sitting areas or paving. It can be formal or informal. If it is formal it should be symmetrical, if informal it should just have a sense of place.

You have to ask yourself the use of the plaza, it can't be just an empty space. Is it an "outdoor foyer" for some big public building, a place of happenings at the intersection of routes or what.

An account on succesful medieval-style plazas and their form/scale can be found in Camillo Sitte's famous book, and there' some good points on the functioning of the public realm in Jane Jacob's the Death and Life of Great American Cities. For starters.

colin rowe's collage city

read chapter: crisis of the object: a predicament of texture

look at the medieval europe

piazza del popolo, rome. i'm sure you can find pics of it on the net, that's the clearest example that comes to my mind, but i might be wrong in my reading of the word...

I'm with Helsinki...it depends on the space's ultimate use and boundary type...allowing for a shift throughout the plaza's life...building use can often come and go, but plazas should adapt. In the US too many plazas must deal with at least one boundary that is a vehicular thourougfare which can help or hurt its ultimate use.

look at the way European cities designate zones for vehicular and pedestrian traffic and how it differs from the US approach. sometimes the biggest obstacle US designers face is the curb or the bollard...these perceived safety factors define the zones...shouldn't it be more or less than that?

some plazas serve as gathering spaces for buildings...ante rooms for lobbies...a progression of outdoor to indoor and vice versa. some are just wide sidewalks and offer little time to linger...some need trees or other shade...some suffer from a lack of scale, some are too cluttered to be effective.

a good question to ask yourself to start the analysis of the polemics of plaza spaces might be: how is this a plaza and how does it serve the same purpose as an outdoor space and why?

http://www.galinsky.com/buildings/statensmuseum/index.htm

The books mentioned are good ones to begin this study, and i can't begin to describe the 'perfect plaza' but i can remember the bad ones...notably Philip Johnson's PPG plaza in Pittsburgh:

http://www.galinsky.com/buildings/ppg/

these photos do the project too much justice...i think those are the only trees within blocks....the main plaza is helplessly devoid of anything...its just vacant and space alone does not a plaza make.

if you are aching for some Renaissance-Era plaza designs, check out:

Formal Design in Renaissance Architecture by Michele Furnari. Its a Rizzoli.

Good spatial diagrams. Stimulates thoughts regarding formal decisions still relevant today.

well. thats a brilliant response to my q. i had an informal plaza in mind, that could take about 250 ppl at any time. i also have a feeling that plazas are defined by the built form around it. its a two way deal between the plaza and the built form.

here is a small entrance plaza.
http://www.artofinhabitation.com/projects/seen/nether022.html

pretty good site with variety of projects, via picture gallery of archinect.
http://www.artofinhabitation.com

abracadabra...thanks for that link, i look forward to checking it out....

k_b...good luck with your plaza. brilliant? i don't know if you're being sarcastic or what.....but if you want to specifically look at plazas with strict built-form boundaries, the renaissance book i mentioned explains those types of spaces quite well. The building relies on the plaza and vice versa, in order to work effectively.

if you are merely treating the plaza as either built or unbuilt/form or space than i guess the black/white duality diagrams work. To me personally, those diagrams should be a lot more complicated involving the way the space is used, the modes of transportation incorporated, sightlines, sun/weather studies, etc...no space is too small to be governed by these design criteria. Best of Luck.

there is nothing as welcoming as a medieval Italian piazza. The scale, the materials, ambiance all work together to create a space that overwhelms the senses. I think the one thing modem plaza's don't do that the medieval piazza's in Italy do is the ease of use. In saying this I mean the ability for any and all activities to occur inside the space. The plaza in front of the pompadu center in Paris is another good example. Plaza's fail without life to fill them, and without activities or the option for activities there will exist no life

hey...instoffaction, i definitely didnt mean to be sarcastic. i was pleased with the response.

This is of a larger scale The new Seattle Central Library has an interesting plaza that is created by an enormous cantilevered overhang...I couldn't find very good images of it but here are a few:

http://www.spl.org/images/branch/CEN_opening/4thAveCrowd280.jpg

http://www.spl.org/images/slideshow/NewCentralSlideshow.asp?index=1

http://www.spl.org/images/slideshow/NewCentralSlideshow.asp?index=0

The sidewalk and plaza are on the same level, but the paving color changes and it slopes down toward the main entry. The interesting thing here is that the space is created mostly by the overhang above, and not by walls...

hi jag
thanks for the links. i personally didnt like the building, but the idea is fantastic. using a cantilever for shading the plaza...and plus, no walls.

glad to hear you're looking into the plaza issue. too often i think architects do not work on how their building is perceived visually beyond their lot line.

i know that this lack of involvement with an adjacent plaza often comes from a lack of control beyond the lotline, but if you have the control...use it. why shouldn't the building respond to the needs of the plaza rather than the other way around...if you can create a space on the exterior that has more significance...i say do so!...Path Portal Place...it all comes back to these basics....best of luck k_b.

well i.o.f. in my case, i am thinking of a plaza that is a gathering point for ppl, before they decide where to go next, what to do next. it is a place to meet others. so i think the plaza is of prime importance, in terms of nature of space. the built form will only lend it its physical form.

sounds great, so your actually designing the plaza rather than the surroundings...be sure to articulate the joint between them...this is often where buildings and plazas fail...where it meets the ground and where it meets the sky.

it sounds as though wayfinding systems will be of importance in your design since its a place 'along the way'...a midpoint between A and B. - always a good challenge.

i just found this link, i hope it interests you... check out the image bank...it may offer some food for thought. The main site also offers some diagrams and other valuable information, although not especially geared toward designers.

http://www.pps.org/imagedb/

thanks a ton, i.o.f. thats a brilliant site

k_b -

I'm still not sold on the new library, and I don't think that the plaza created by the cantilever is very successful, but I thought it is a great example of thinking about how that space can be created without walls as you pointed out...Not only is the space shaded(at some parts of the day) the heaviness of the building above really does help define that space...I took a look again yesterday, and there is a dramatic color difference in paving as well...and a raised planting area in the center along the edge of teh sidewalk. There are also several small trees under the cantilever and it will be interesting to see how that space changes as the trees mature.