The main SIGIR'98 activities all take place in Melbourne's central business district. These locations (the Sofitel Hotel, the Melbourne Town Hall, and Le Meridien Hotel Ballroom at the Rialto Building) are marked in red on the map below, in addition to the Novotel and Ibis hotels.
The Town Hall is an easy five minute walk downhill from the Sofitel Hotel. For travelling further afield, Melbourne has an extensive public transport system: tram routes in the central Melbourne area are marked on the map. In addition, there is a free City Circle tourist tram which operates regularly along Flinders, Spring, Latrobe and Spencer Streets.
A map with slightly more coverage is available in Postscript format. The Tourist Information section of the SIGIR'98 web pages has more information about Melbourne.