Honor Award

General Design

Potomac, MD, USA
PWP Landscape Architecture
Client: Glenstone Foundation

"In this private museum in Potomac, Maryland, set amid 230 acres of rolling hills, streams, meadows, and woodland paths, the landscape architect has integrated the natural environment, architecture, and works of art into a seamless sensory and intellectual experience. Though large in scale, the project’s power comes from its restraint and its contemplative character. This is a museum site where the natural world is in the foreground, creating a visitor experience that extends beyond art and architecture. Glenstone is an impeccably composed landscape, with its beautiful interior Water Court and two miles of walking paths, trails, and bridges that pass through a dynamic landscape of 8,000 trees and indigenous plants, all punctuated by world-class art."

- 2019 Awards Jury

Project Credits

  • Architect of The Pavilions: Thomas Phifer and Partners Architect of The Gallery: Charles Gwathmey, Gwathmey Siegel & Associates Architects, Arborist: Bartlett Tree Experts, Civil Engineering: VIKA, Inc., Consulting Ecologist: Jeffrey Wolinkski, Geotechnical Engineering: Schnabel Engineering DC, Graphic Design: 2x4, Irrigation: Sweeney & Associates, M/E/P/FP Engineering: Altieri Sebor Wieber LLC, Master Stone Mason: Philip Dolphin, Pond Wall Mason: Travis Callahan, Meadow Consultant: Larry Weaner Landscape Associates, Owners Representative: MGAC, Soil Scientist: Pine & Swallow Environmental, Stream Restoration Construction: Aquatic Resource Restoration Company, Structural Engineering: Skidmore, Owings & Merrill, LLP, Sustainability: Buro Happold, Water Court / Constructed Wetland Engineering: Biohabitats, Waterproofing: Henshell and Buccellato

Project Statement

The Glenstone landscape integrates art, architecture and nature within a continuum of cultural experience and expression. An evolving spatial and sensorial journey unfolds as visitors leave their cars in the shade of a designed woodland and traverse this 200-acre designed landscape on foot. Through physical contact with the land as well as key moments of prospect across it, reflection on, and understanding of, landscape systems is foregrounded alongside world class art and architecture.

Project Narrative


Potomac, Maryland; Completion, 2018

Located on 230 acres in Potomac, Maryland, near Washington DC, Glenstone is a museum of modern and contemporary art that offers visitors a seamlessly integrated experience of works from its collection including architecture, and landscape. The Glenstone landscape design integrates art, architecture and nature within a continuum of cultural experience and expression. An evolving spatial and sensorial journey unfolds as visitors leave their cars in the shade of a designed woodland and traverse the landscape on foot. Through physical contact with the land as well as key moments of prospect across it, an understanding of landscape systems is foregrounded alongside world class art and architecture.

Over the last 15 years, the landscape architect worked collaboratively with teams of design professionals, artists, ecologists and a non-profit foundation to transform 230 acres of planned residential-subdivision plots into an integrated experience of rolling topography, native meadows, wetlands, singular architecture, and site-specific sculpture. The site exists within a formerly rural landscape of agriculture and the undulating topography of the Potomac River Valley. Over the last century, suburban enclaves transformed this area into an assemblage of small one-to-five-acre plots that weakened the ability to perceive the natural morphology of the region. When the owner acquired the property, it had been graded to receive single-family subdivision houses; a topography of level plateaus and engineered slopes between them. In addition to the original property, more than a dozen suburban home sites were added to the project and have been transformed, knitting together formerly disparate, resource intensive suburban estates into one ecologically and socially productive landscape defined by watersheds.

Glenstone creates a new kind of museum experience where visitors are engaged in the landscape from the moment they arrive, encouraging them to set aside everyday concerns. Restoring the land itself as well as the people, plants and animals that inhabit and traverse the site, Glenstone embodies the ability of designed landscapes to sustain both culture and the natural environment. The new landscape design integrates walking paths, bridges and restored meadows and woodlands. More than 6,000 trees of 55 native species have been planted across the grounds, bringing the total installed at Glenstone to over 8,000. Approximately 33 acres of existing lawn and pasture land have been developed into sustainable meadows with a range of indigenous flora. The Pavilions' Water Court is richly planted with water lilies, irises and rushes, creating a dynamic landscape that changes throughout the seasons. The visitor entrance is framed by dry-stack stone walls constructed by a master craftsman with stone sourced from a nearby quarry.

From the Pavilions, visitors may continue on a short path to the Café. Like the Arrival Hall, the Café has an exterior of cedar, which will continue to weather to a soft gray that echoes the color of the Pavilions' exterior. Visitors are able to proceed past the Café to the original museum building, the Gallery, which continues to house temporary exhibitions of works from Glenstone's collection. Past the Gallery is an additional café space, the Patio, where visitors may enjoy coffee or a snack or refresh themselves before touring the landscape. Within the landscape, over two miles of paths and walking trails bring visitors into contact with a variety of natural phenomena as well as site specific art. Sculpture, installations and audio pieces are set within the landscape. At times specific sites were designed for the art, whereas in other instances, art has been placed within pre-existing landscape spaces.

The landscape design and implementation emphasize a systems approach to water management, reforestation, meadow regeneration, and landscape maintenance. Significant time was spent on horticultural and ecological design. Over 400 existing specimen trees were transplanted on site, meadows were both constructed and restored and existing water bodies were ecologically renewed to filter runoff and to create improved habitat for a range of native plants and animals. The re-use of the existing trees is representative of the project's goal to be innovative and sustainable in its construction and management. Through careful coordination in documentation and observation on site, trees ranging in size from five-inch to 30-inch caliper were moved, stored, and replanted. Since all the largest caliper trees came from the site itself, they were adapted to the site conditions and its soils. Most of the 8,000 additional planted trees were smaller caliper and thus highly adaptable. Grading, planting, and storm-water management strategies were conceived as parts of an integrated landscape system so that Glenstone requires less water and energy to maintain. The meadows slow and direct runoff to bioswales and detention ponds and do not require supplemental irrigation. The meadows do require considered management, but not frequent maintenance.

Site wide, rain water is collected and re-used for irrigation. The lawn area that situates the Gallery and the private residence slopes toward the largest pond on site. Irrigation runoff is filtered through the stone wall on one side of the pond and the planted wetland edge on the other. Roof runoff from the Gallery is directed to this pond which supplies water to the irrigation system. At the Pavilions, roof runoff and meadow surface drainage is collected in three below-grade cisterns. The site maintenance regime now consists of an all-organic program, leading to a net positive impact on the environment.


Product Sources: N/A

Plant List


  • Potomac, Maryland; Completion, 2018


  • Acer negundo Boxelder
  • Acer rubrum Red Maple
  • Acer saccharum Sugar Maple
  • Asimina triloba Pawpaw
  • Betula Nigra River Birch
  • Carpinus caroliniana American Hornbeam
  • Carya glabra Pignut Hickory
  • Carya ovata Shagbark Hickory
  • Celtis occidentalis Hackberry
  • Cercis canadensis Redbud
  • Chionanthus virginicus Prodigy Fringetree
  • Cladrastis kentukea Yellowwood
  • Cornus florida Flowering Dogwood
  • Cryptomeria japonica Japanese Cryptomeria
  • Diospyros virginiana Common Persimmon
  • Fagus grandifolia American Beech
  • Fagus sylvatica Copper Beech
  • Franklinia alatamaha Franklin Tree
  • Gleditsia triacanthos var. inermis Thornless Honeylocust
  • Gymnocladus dioicus Kentucky Coffee Tree
  • Halesia tetraptera Carolina Silverbell
  • Juniperus virginiana Eastern Redcedar
  • Liquidambar styraciflua Sweetgum
  • Liriodendron tulipifera Tulip Poplar
  • Magnolia virginiana var. australis Sweetbay Magnolia
  • Malus 'Adams' Flowering Crabapple
  • Nyssa sylvatica Black Gum
  • Ostrya virginiana American Hophornbeam
  • Pinus strobus White Pine
  • Pinus taeda Loblolly Pine
  • Pinus virginiana Virginia Pine
  • Platanus occidentalis American Sycamore
  • Platanus x. acerifolia 'Columbia' Columbia Plane Tree
  • Quercus nuttallii Nuttall's Oak
  • Quercus alba White Oak
  • Picea abies Norway Spruce
  • Quercus bicolor Swamp White Oak
  • Quercus lyrata Overcup Oak
  • Quercus macrocarpa Burr Oak
  • Quercus montana Chestnut Oak
  • Quercus phellos Willow Oak
  • Quercus velutina Black Oak
  • Robinia pseudoacacia Black Locust
  • Salix babylonica Weeping Willow
  • Sassafras albidum Sassafras
  • Taxodium distichum Bald Cypress
  • Tilia americana American Basswood
  • Ulmus parvifolia Chinese Elm


  • Calycanthus floridus Carolina allspice
  • Cephalanthus occidentalis Buttonbush
  • Clethra alnifolia 'Hummingbird' Summersweet
  • Corylus americana American Hazelnut
  • Euonymus americanus Strawberry Bush
  • Fothergilla x intermedia 'Mt. Airy' Mt. Airy Fothergilla
  • Hamamelis virginiana Common Witchhazel
  • Hamamelis x intermedia 'Arnold Promise' Arnold Promise Witchhazel
  • Ilex glabra 'Chamzin' NORDIC Inkberry Holly Cultivar (male)
  • Ilex glabra 'Compacta' Inkberry Holly Cultivar (female)
  • Ilex opaca 'Judy Evans' American Holly cultivar
  • Ilex opaca 'Maryland Dwarf' American Holly cultivar
  • Ilex verticillata 'Southern Gentleman' Winterberry Holly cultivar (male)
  • Ilex verticillata 'Winter Red' Winterberry Holly cultivar (female)
  • Ilex x. 'Nellie R. Stevens' Nellie R. Stevens Holly
  • Itea virginica 'Henry's Garnet' Henry's Garnet Virginia Sweetspire
  • Lindera benzoin Spicebush
  • Myrica pensylvanica Northern Bayberry
  • Osmanthus americanus Devilwood
  • Prunus laurocerasus 'Schipkaensis' Schip Laurel
  • Rhododendron maximum Rosebay Rhododendron
  • Viburnum nudum 'Winterthur' Winterthur Smooth Witherod


  • Allium cernuum Nodding Onion
  • Amsonia hubrichtii Threadleaf Bluestar
  • Andropogon ternarius Splitbeard Bluestem
  • Anemone canadensis Canada Anemone
  • Asclepias tuberosa Butterfly Weed
  • Asclepias verticillata Whorled Milkweed
  • Aster azureus Sky Blue Aster
  • Aster divaricatus White Wood Aster
  • Aster macrophylllus Big Leaf Aster
  • Aster oblongifolius Aromatic Aster
  • Aster laevis Smooth Aster
  • Aster patens Late Purple Aster
  • Athyrium felix-femina Lady Fern
  • Baptisia alba White Wild Indigo
  • Callisia rosea Piedmont Roseling
  • Carex annectens var. xanthoca Yellow Fruited Sedge
  • Carex bebbii Bebbs Oval Sedge
  • Carex brevior Plains Oval Sedge
  • Carex grayi Gray Sedge
  • Carex pennslyvanica Pennsylvania Sedge
  • Carex projecta Loose-headed Oval Sedge
  • Carex radiata Eastern Star Sedge
  • Carex stricta Tussock Sedge
  • Carex vulpinoidea Fox Sedge
  • Chrysogonum virginianum Green and Gold
  • Coreopsis lanceolata Tickseed
  • Coreopsis major Greater Tickseed
  • Dennstaedia punctiloba Hay Scented Fern
  • Deschampsia cespitosa Tufted Hairgrass
  • Deschampsia flexuosa Wavy Hair Grass
  • Dryopteris goldiana Goldie's Woodfern
  • Dryopteris marginalis Marginal Woodfern
  • Echinochloa crusgalli Barnyard Grass
  • Elymus canadensis Canada Rye
  • Erigeron pulchellus Robin's Plantain
  • Eryngium yuccifolium Rattlesnake Master
  • Eupatorium hyssopifolium Hyssop-Leaved Thoroughwort
  • Eupatorium coelestinum Hardy Ageratum
  • Eupatorium fistulosum Joe-pye Weed
  • Euphorbia corollata Flowering Spurge
  • Euptorium dubium 'Little Joe' Dwarf Joe-Pye Weed
  • Euthamia graminifolia Grass-Leaved Goldenrod
  • Festuca obtusa Nodding Fescue
  • Festuca rubra var. rubra Strong Creeping Red Fescue
  • Geranium maculatum Wild Geranium
  • Geum fragarioides Barren Strawberry
  • Helianthus angustifolius Swamp Sunflower
  • Hordeum jubatum Foxtail Barley
  • Iris cristata 'Powder Blue Giant' Dwarf Crested Iris
  • Itea virginica 'Little Henry' Little Henry Virginia Sweetspire
  • Liatris spicata Blazing Star
  • Liatris aspera Rough Blazingstar
  • Liatris pilosa Shaggy Blazing Star
  • Lobelia cardinalis Cardinal Flower
  • Mertensia virginica Virginia Bluebells
  • Mondarda punctata Horsemint
  • Muhlenbergia capillaris Hair-awn Muhly
  • Onoclea sensibilis Sensitive Fern
  • Osmunda cinnamomea Cinnamon Fern
  • Osmunda regalis Royal Fern
  • Panicum rigidulum Red-Top Panic Grass
  • Penstemon digitalis Foxglove Beardtongue
  • Penstemon laevigatus Eastern Smooth Beardtongue
  • Phlox divaricata Wild Blue Phlox
  • Polemonium reptans Jacob's Ladder
  • Polystichum acrostichoides Christmas Fern
  • Pycnanthemum incanum Hoary Mountain Mint
  • Pycnanthemum tenuifolium Slender Mountain Mint
  • Pycnanthemum virginianum Virginia Mountain Mint
  • Rudbeckia hirta Black Eyed Susan
  • Schizachyrium scoparium Little Bluestem
  • Senecio aureus Golden Groundsel
  • Silene stellata Starry Campion
  • Smilacena racemosa False Solomon's Seal
  • Solidago caesia Blue-Stemmed Goldenrod
  • Solidago nemoralis Gray Goldenrod
  • Solidago rigida Stiff Goldenrod
  • Solidago speciosa Showy Goldenrod
  • Thelypteris noveboracensis New York Fern
  • Tradescanita virginiana Virginia Spiderwort
  • Tridens flavus Purpletop Tridens
  • Vernonia noveboracensis New York Ironweed
  • Zizia aptera Golden Alexander
  • Zizia aurea Golden Alexander