Tallinn is Estonia's capital which has retained its medieval walled cobblestoned Old Town which is considered an Old World Treasure and UNESCO heritage site. It is built on a limestone hill and is lined picturesque churches, merchant's houses and underground tunnels. It provides the perfect photo opportunities and the chance to sample some unique food and drink. The longest tunnel in the world measuring between 93-103Kms Helsinki-Tallinn railway tunnel should be inaugurated in the 2030s at a cost of 15b Euros.