No active volcanoes have been found on Venus to date but evidence seems to suggest that some do exist. Gula Mons is a massive shield volcano on Venus. The caldera at the summit is over 100 km across. The volcano is about 4 km high. This image was produced by the 3D imaging of Magellan.
Vertical scale is greatly exaggerated.
There are two pieces of evidence that point to volcanism still taking place on Venus. Levels of sulfur dioxide in the atmosphere show variations. One spacecraft measured very high levels of sulfur dioxide but levels dropped off over time. Sulfur dioxide is a gas commonly released in volcanic eruptions. On Earth, when a volcano erupts, our atmospheric levels of this gas rise.