It was more evident but the declivity of the road has been smoothed out a little. Much more modern, is the bypass road which joins from the south at the entrance to the town and just below the level of the surface of the former lake. This opened for use on 8 October 2005. In the town, the A151 passes immediately outside the castle site, along the latter's northern edge. However the plots along this side of the road were first laid out for houses in around 1280, so that the castle is no longer casually apparent. At Bourne Market Place, the A151 crosses the A15. This road used to be part of the Lincoln Heath to Peterborough turnpike road, whose act of parliament is dated 1756. It was this trust which, in 1820, demolished the old town hall which used to stand in the street here. At the junction, the road to the north led directly form the main gate of the castle. The market place was positioned immediately across a moat and a pomœrium, outside the gate but those are no longer visible from the road. However, our road continues not straight ahead but on a 45° angle toward the south. This bend arose because it passed around the perimeter of the pomœrium until it met the road leading eastwards from the gate. As the A151 reaches this, it turns back through 45° and continues eastwards along that approach road, across the line of the Roman version of the A15, King Street and past the Abbey Lawn. This is now a picturesque cricket ground, but was an 18th-century sheep lawn. Soon, the road leaves the 12th century, Norman road, heading towards the pre-Norman town. On arrival, it turns eastwards again, at the same time as crossing the now-buried course of the Car Dyke and onto the fen-edge gravel. This is material which drifted down the slope which we have followed, while it was under the water of the Devensian periglacial lake. The Car Dyke is generally taken as the boundary of The Fens, though here, it heralds the more commercial part of the town. At once, the road passes the former works of BRM, the Formula One motor racing Constructors' Champion in 1962. The firm is gone but it has left an engineering tradition in the town. Shortly, the road turns north-eastwards, following the bank of the Roman