United States National Arboretum

Listen for a moment. Beneath the traffic noise of northeast Washington, there is a softer layer of sound: wind moving through tall oaks, the dry crunch of gravel under your shoes, and birdsong from somewhere deep in the trees. The air here often smells of cut grass and damp earth. It is hard to believe that the city's busy avenues are only a short walk away. This is the United States National Arboretum. It is a living museum where the collection is made of trees, shrubs and flowers.

The arboretum was created by an Act of Congress in 1927. Its mission was practical as well as beautiful. Scientists wanted a place to study plants, breed better ones, and preserve rare varieties for the future. Today the site is run by the Agricultural Research Service, the research arm of the United States Department of Agriculture. So while you are strolling, remember that this is also a working research station. Some of the plants around you are part of long-running scientific programs.

The grounds are large — nearly 450 acres of rolling hills, meadows and woodland. The Anacostia River runs along one edge. Roads loop through the property, and many visitors drive or cycle between the different gardens. That size is the first surprise for many people. In a capital known for marble monuments, this is one of the largest open green spaces inside the city. You could spend a whole day here and still miss entire corners.

Now for the strangest sight on the grounds. In the middle of a wide, open meadow stands a group of tall stone columns. They hold up nothing. They simply rise from the grass in a quiet rectangle. These are the National Capitol Columns. They once stood on the East Portico of the United States Capitol, the side of the building where many presidents took the oath of office.

In the late 1950s, the Capitol's east front was extended. The original sandstone columns were taken down and replaced. For years, the old columns lay in storage, almost forgotten. Later, a group of supporters brought them here. The English garden designer Russell Page helped create their setting, with steps, a reflecting pool and a small channel of water. Think about that for a moment. The stone in front of you once looked down on presidential inaugurations.

Stand close and look at the surface of the stone. Sandstone is soft, and it carries the marks of weather and time. You can see worn edges, small cracks and patches of different colour. At sunrise and sunset, the stone turns warm gold, and long shadows stretch across the meadow. Many photographers come at those hours. Even at midday, the columns look like the ruins of an ancient temple dropped into an American field.

The second treasure is smaller, but just as moving. The National Bonsai and Penjing Museum holds a collection of miniature trees from Japan, China and North America. Penjing is the Chinese art of shaping small trees and landscapes in containers, and it is older than Japanese bonsai. The museum began with a gift of bonsai from Japan for the American Bicentennial in 1976. It was a gesture of friendship between the two countries.

One tree in that original gift carries an extraordinary story. It is a Japanese white pine that is centuries old. It was kept by a family in Hiroshima, and it survived the atomic bombing of 1945. For many years, the museum did not know this history. It came to light only decades later, when members of the donor's family visited. Stand in front of that small pine, and you are looking at a living survivor of one of the darkest days of the twentieth century.

If you visit in spring, head for the slopes of Mount Hamilton. This hill is covered with azaleas, and in their season the hillside fills with pink, white, red and purple blossoms. The paths climb through the shade of tall trees. From the higher ground, you may catch a view of the Capitol dome rising in the distance. It is a reminder that this quiet place sits inside the nation's capital.

For something wilder, look for Fern Valley. This area focuses on plants native to the eastern United States. A trail runs along a small stream under a dense canopy. In summer it feels cool and green, with ferns spreading across the forest floor. It shows what much of this region looked like before cities and farms. Near by, you will also find an herb garden, where the air often smells of mint, lavender and other aromatic plants.

Other collections have their own character. The Asian Collections bring together trees and shrubs from China, Japan and Korea, set on a hillside above the river. The Gotelli collection gathers dwarf and slow-growing conifers — evergreen trees with needles and cones — in surprising shapes and shades of blue, gold and green. The National Grove of State Trees aims to represent each state with its official tree. Each garden feels like a different room in a very large house.

The arboretum changes completely with the seasons. Spring brings magnolias, cherries and azaleas. Summer is deep green and humid, with the sound of insects in the meadows. Autumn turns the maples and oaks red and amber. Even winter has something to offer. Bare branches show the structure of each tree, and the evergreen collections stand out against the grey sky. Many local people return again and again simply to watch these slow changes.

Before you move on, pause wherever you are standing. Notice the light as it falls through the leaves or across the open grass. Listen again for the wind and the birds. Everything around you was planted, studied and cared for by people who were thinking decades ahead. As you walk back toward the road, look at the trees one more time. Some of them were here long before you arrived, and many will still be growing long after you leave.