What is the oldest tree in Graz?
Graz's most solidly dated protected tree is the Augarten Field Maple, growing at the eastern edge of the Augarten park in the Jakomini district. Its formal legal protection dates to 1979, but Wikipedia's own record of Graz's protected trees cites an earlier source, a 1956 survey of the city's planted broadleaf trees, which already listed this exact maple as worth protecting. That gives it a documented floor of at least seventy years old, decades before most of Graz's other protected trees, whose designation dates cluster in 1979, 1990 and 2000 with no age ever published for the trees themselves. Two oaks on Panoramagasse, protected on the same day in July 1979, carry real 2015 field-measured girths (2.80 and 4.90 metres), and those measurements now date them: at the published growth rate for oak they come out at roughly 100 to 200 years and roughly 175 to 350, which puts the larger one older than the maple on the arithmetic while the maple keeps the better paper trail. Both are bands a century or more wide, because that is the honest width of a girth estimate.
This page is built on the City of Graz's own live Naturdenkmale open-data register (geodaten.graz.at, CC BY 4.0), cross-checked tree by tree against Wikipedia's independently maintained 'Liste der Naturdenkmaler in Graz', which geocodes each entry separately and sometimes carries a real field measurement or historical citation the register itself lacks. This page publishes sixteen trees: ten around the city centre, spanning the Schlossberg hill, the Volksgarten park, the Augarten, Schillerplatz, Elisabethstrasse and the Panoramagasse hillside, and three more on the western side near Schlosspark Eggenberg, a UNESCO World Heritage palace park about 3.5km west, where a wider planting of ten designated trees yielded only one pine and one beech with documentation strong enough to publish, plus a free oak in a public park 900 metres from the palace gate, and two in the eastern hills, a sweet chestnut by the Lustbühel and a cornelian cherry on the Johannhöhe ridge, each known from the register and a dated photograph, plus a lone Oriental plane on Münzgrabenstrasse in Jakomini. The remaining eight Eggenberg trees (five planes, three pines) share an address and a date but no individuating record, reading as one avenue rather than separate points.
One of Graz's trees also appears in Autumn Worth the Trip.