The town is built on igneous rock in the James Valley, sandwiched between steep cliffs. It is therefore rather long and thin. The walls of the valley are rough and steep, and rockfalls have been a problem, although now minimised by netting. A small stream, the ''Run'', runs through the valley. The town is commonly divided into lower and upper parts, depending on the distance up James Valley. Being the island's main port (and with the Saint Helena Airport only receiving its first scheduled flight in October 2017) the town is still currently the main entrance to the island to visitors. Despite not being connected to Jamestown proper by road, Rupert's Valley, the next valley north, is also part of the town. It houses much of the island's infrastructure, such as its power station and associated fuel storage, and a one-ship wharf was completed in June 2016.