Almost every building in downtown Baltimore bears the signature of a Swiss surveyor and mapmaker.
Simon Jonas Martenet was a fastidious draftsman and a genius at establishing razor-perfect property lines. The land surveying firm he founded in 1849 is considered by many to be the final word on who owns what.
Housed in a roomy South Baltimore office, S.J. Martenet & Co. is a kind of combination U.S. Supreme Court and Smithsonian Institution of Baltimore's boundaries. Its voluminous records, which survived the 1904 Baltimore Fire, pinpoint everything from the first pile driven at Memorial Stadium to home plate at the old Oriole Park on 29th Street.
"If a piece of land ever changed hands in downtown Baltimore, I think we have a record of it," said Joel M. Leininger, one of three partners who purchased the Martenet firm several years ago.
"This is an amazing place. I come down here on Saturdays when it isn't busy just to get an idea of the history we've got stored here," he said.
There's acres of Baltimore history -- by no means all related to the commercial parts of town -- housed in the firm's towering wooden cabinets, map racks and document cases.
"Govans is ours. So is Ednor Gardens. Glen Burnie and Aberdeen, too. We laid out the outlines of Roland Park. . . . I almost forgot. We did Fairfield, too," said Mr. Leininger.
"We're the only kind of commercial firm whose old records grow more valuable each year."
Mr. Leininger works with his partners, David S. Paplauckas and Thomas L. Wilhelm, and two longtime Martenet surveyors, Howard and Richard Tustin. The Tustins once owned the firm but sold it to the younger trio.
"The Martenet partners got rich after the 1904 fire. The city was in ruins and they were doing five and 10 surveys a day," Richard Tustin said.
He recalled the stories told by older surveyors, who related that on Feb. 7, 1904, they drove horses and wagons to their office in the Equitable Building office and removed as many of the firm's records as they could before the building was destroyed by the famous Baltimore Fire. They were able to save a staggering amount of material, but not all.
Lost was a complete set of highly detailed maps of various Maryland counties made and published by S.J. Martenet in the 19th century.
Today, the rescued volumes are prized by collectors and students of cartography.
Mr. Martenet, who was born in Neufchatel, Switzerland, had a voracious appetite for work. In addition to all his survey and map-making activity, he bought and developed an area he named Parkville, today a thriving Baltimore County community. The firm's founder signed all his work with a distinctive, flowing signature. That line of script has been retained to this day on Martenet surveys.
By looking through the firm's records, which are consulted daily by its cartographers, it's possible to trace neighborhood histories. A fine example is the Ednor Gardens neighborhood, just north of Memorial Stadium, that is known for its gray stone houses. Mr. Martenet initiated survey work here in the 1920s.
The Ednor plats sketch an unconstructed street called Del Monte. By the 1930s, its name had become Delmonte. By the 1950s, when the road was finally cut and homes built on it, it took its final form, Delverne Road.
Mr. Martenet's Feb. 6, 1914, blueprint for Terrapin Park in the 300 and 400 blocks of E. 29th St., shows a home plate 425 feet from dead center field. The fabled home of the Baltimore Orioles' of the International League burned down July 4, 1944. Its site today is the Barclay Elementary School and several industrial buildings. They, too, were surveyed and signed in the flowing Martenet script.
"You've got to love city history to work here. That's the only way it is," Mr. Leininger said.