In the late tenth century, on the western coast of Zealand, King Harald Bluetooth built a fortress that must have looked to its neighbours like a statement written in earth. Trelleborg is a perfect circle, about a hundred and thirty metres across, ringed by a high rampart with four gates facing the compass points, and inside, sixteen long houses are arranged in four neat blocks around a central crossing, like a plan drawn with a compass and ruler. Archaeologists dated the timbers to around the 980s, and the same geometry turns up at other Danish fortresses, at Fyrkat in Jutland and Aggersborg by the Limfjord, which suggests a royal building programme under a single mind.
The purpose is debated. It may have been a base for a standing army, or a place to gather men and ships for campaigns, or a show of the king's power at the Great Belt crossing, which was an essential route. What is clear is that the fort was used for a short time, perhaps a few decades, and then abandoned. The visitor centre has a reconstructed longhouse with a turf roof and a museum of Viking Age finds, and the ramparts have been reconstructed so that you can walk the full circle. The site is part of the UNESCO listing of the Viking-Age Ring Fortresses of Denmark.
The country around is soft and green. Zealand's southwest is low farmland, with fields of barley and rapeseed, small woods and lakes, and the Great Belt on the horizon. The roads are quiet and straight, with the occasional turn at a farm or a village, and not a hill in sight, so the pleasures are the sky, the wind and the cycle paths. Summer is the best season, and weather can come in fast from the west. Speed limits are strictly enforced in Denmark, with fixed cameras and patrols, and fines are heavy.
Forlev, two kilometres away, is a small village, and Slagelse, six kilometres off, is the larger town, with fuel stations, supermarkets, a museum and a historic centre with a medieval church. Skælskør and Korsør are the nearby harbour towns, and the Great Belt Bridge, on the east side, is a long toll crossing for motorbikes. Try a smørrebrød open sandwich, and in the afternoon a kanelsnegl, a cinnamon pastry. The site is open daily in summer with a modest fee, and the wind on the rampart is often strong, so bring a windproof layer.