Most people visiting Grisslehamn come for the beautiful views of the Swedish archipelago or Engström’s house. While walking around, visitors may stumble upon a wooden hut with strange panels above it. These are not solar panels, but optical shutters. This building is a replica of the optical telegraph that once connected Åland to Stockholm. 

Grisslehamn was once an important communication hub in Sweden, sending information eastward as fast as possible. At first, this was done orally and with letters, then onto telegraphs and phones, however, there was one strange step in this evolution, the optical telegraph. 

The system was invented in 1794 by Abraham Niclas Edelcrantz and used a binary number system that allowed it to send messages rapidly with the 10 shutters on its roof, which could be set in 1,024 different combinations. Each station was just within view of the next. Using binoculars, an operator would copy the often coded message so that the next station could view it as well. Using this method, a message could travel through the country in minutes, where normally it would take hours or even days. The technology was revolutionary until the telegraph was invented in 1837.

The Grisslehamn optical telegraph was inaugurated in 1796, part of a larger chain to the capital. The replica was inaugurated in 2015 in a location close to the original.