1. The Old Stone Bridge in Regensburg, Germany is a medieval bridge that spans the Danube River. It is around 310 meters long and was built between 1135 and 1146, making it one of the oldest stone bridges in the country. The bridge is an impressive example of medieval architecture and engineering, with 16 arches and a picturesque tower on the southern end.

2. The Old Stone Bridge is open to the public at all times and does not have specific working hours. However, it is advisable to visit during daylight hours for the best views and photo opportunities. Unfortunately, there is no specific phone number available for inquiries about the bridge.

3. There is no entrance fee or ticket required to visit the Old Stone Bridge in Regensburg. The bridge is easily accessible on foot from the Old Town area of the city, and there are also public transportation options available. Visitors can take a bus or taxi to the bridge, or simply enjoy a leisurely walk along the banks of the Danube River to reach this historic attraction.