Mount Sylvania is an extinct volcano, part of the Boring Lava Field, on the outskirts of Portland, Oregon. Parts of the mountain are within the cities of Portland, Lake Oswego, and Tigard. The Sylvania campus of Portland Community College is located on the mountain's western slopes. References External links Volcanoes of Oregon Mountains of Oregon Subduction volcanoes Cascade Volcanoes Volcanoes of Multnomah County, Oregon Volcanoes of Clackamas County, Oregon Lake Oswego, Oregon Shield volcanoes of the United States Mountains of Clackamas County, Oregon Landforms of Multnomah County, Oregon