Peruskiven

Peruskivi is the Finnish term for a cornerstone or foundation stone used in construction to mark the start of a project. Traditionally a peruskivi is placed at the corner of a building's foundation and then ceremonially blessed or inaugurated to symbolize stability and endurance. The stone is usually a durable material, such as granite or marble, and may bear inscriptions with the project name, date, and the names of key participants, sponsors, or authorities. In many cases a time capsule or commemorative message is embedded in or near the foundation.

Today the concept continues to play an important role in architectural culture and public life in Finland. A peruskiven ceremony often coincides with the start of construction and may be attended by politicians, municipal leaders, developers, architects, and donors. The portrayal of such ceremonies emphasizes the project's significance and community investment.

In addition to its literal meaning, peruskivi is used metaphorically in Finnish to refer to a foundational element of a plan, organization, or policy. The term is thus part of both technical architectural language and everyday speech.