Oldest U.S. Suspended Pavement Installation

The Christian Science Center, on Huntington Ave between Mass Ave and Belvidere Street in Boston, is the oldest suspended pavement installation that we know of in the United States. These trees were planted in 1968, making them 43 years old.

Sasaki & Associates designed this site to include the soil trenches, which are made up of structural slabs resting on grade beams over a garage roof. James Urban and Al Key visited this site at the end of July and determined that all or almost all of the trees are original and in good condition. Each tree has access to around 800 cubic feet (22.6 cubic meters) of soil.

They have been heavily pruned throughout the years to keep the canopy in balance with the rooting space. The canopy is also pruned to reduce significant branching on the middle row of trees so that the trees grow at an even rate.

The trees are incredibly well maintained by the Christian Science grounds crew. Realistically, this level of maintenance would not be duplicated on a normal project. Still, with a few design tweaks and on sites where uniformity and proportion are not the top priority, the maintenance demands would be much smaller.

These trees are stunning and are an obvious attraction to this site (particularly on a hot summer day). We cannot wait to see what some of the trees on the Silva Cell sites look like 50 years from today.

All images: James Urban


  1. Gillis Dellebeke

    Can you explane me the details of the construction

    • Leda Marritz

      Unfortunately we don’t know much about the construction, except that it’s a reinforced concrete post-and-beam system.

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