Kotlin Island is only about twelve kilometres long and rarely more than a kilometre or two wide, and every metre of its northern shore was given over to guns. A numbered battery like this one is the sort of thing that appears on a map as a dull label and turns out to be a lump of overgrown concrete and earth, with ammunition stores half buried in the ground and a view across a shallow, pewter-coloured sea. Kronstadt, four or five kilometres away, was founded by Peter the Great in the first years of the eighteenth century to keep Swedish ships out of the new capital's approaches, and the fortifications grew in layers for the next two hundred years.
What makes these northern defences interesting is that they were obsolete almost as soon as they were finished. Rifled guns, then steel ships, then aircraft kept moving the goalposts, so every generation built another ring and left the old one to rust. Walk the paths and you can read the history in the masonry: granite blocks from the age of sail, red brick from the nineteenth century, grey reinforced concrete from the twentieth. The trees have taken over the earthworks, and in summer the whole thing is green and humming with insects.
Riding here is flat and quiet, a matter of single-lane roads between low fences and scrubby woodland, with sudden gaps that show the water. The surface is patchy, with frost damage and sand blowing across the tarmac near the shore, so treat any corner cautiously. Traffic is light apart from the occasional truck. Wind from the gulf is the main enemy; on a cold day it will find every gap in your jacket.
For fuel and food you want Kronstadt itself, a town of about forty-three thousand with petrol stations and plenty of small cafes. The towns on the mainland, Gorskaya and Aleksandrovskaya, are smaller. Bring a layer even in July, because the sea breeze here can feel like October.