The Choate Bridge has been carrying traffic over the Ipswich River since long before anyone here owned a mower, and the lawns around it are old ground — small, walled, shadowed by houses with steep seventeenth-century roofs. McCarthy & Son Landscaping, Inc. works those yards with a light hand: mowing, trimming close to stone and sill, edging the paths, keeping the beds mulched and the borders defined. April brings the cleanup, when everything the winter dropped comes off and the turf gets its air back. By the time the shad trees are blooming downtown, the lawns are cut and holding their color. Streets this old deserve that kind of attention.