Italy has some of the most difficult environments for GPS I have ever seen. Narrow alleys with 5+ story buildings. I have not been able to find restaurants usin

Italy has some of the most difficult environments for GPS I have ever seen. Narrow alleys with 5+ story buildings. I have not been able to find restaurants using GPS to guide me, or even the block they are on. It's due to multipath and limited sky view. In open sky GPS accuracy would be about the same in the North America and Italy. There is a GPS correction service used in Europe and North America called SBAS. If you outside an area with SBAS (for example China) you will typically get a meter or two less accuracy. China has a different map datum that can be 1KM off due to some cold war era policy that now seems more about protectionism. Other than China map datums are consistent with GPS positions.