The first phase of a proposed eastern bypass for the city is the Dublin Port Tunnel, which officially opened in 2006 to mainly cater for heavy vehicles. The tunnel connects Dublin Port and the M1 motorway close to Dublin Airport. The city is also surrounded by an inner and outer orbital route. The inner orbital route runs approximately around the heart of the Georgian city and the outer orbital route runs primarily along the natural circle formed by Dublin's two canals, the Grand Canal and the Royal Canal, as well as the North and South Circular Roads.