Coming to Marseille:
The main railway station for the Marseille metropolitan area, Marseille Saint-Charles is connected to the regional/national network by Intercity trains, TERs and TGVs. As an example, a direct train connects Marseille to Paris in 3 hours 30 minutes or to Barcelona in 4 hours 30 minutes and Marseille can be reached by train from many European cities such as Berlin, London or Madrid in a single day of travel. Marseille Saint-Charles station is at 15 minutes from the Old Port of Marseille by taking the M1 metro and 20 minutes directly walking.
Coming to the Palais du Pharo from the Old Port of Marseille:
From the Old Port metro station (View Port), you can take the bus 82/82S and reach the Pharo in 10 minutes + 2 minutes of walking, or in 20 minutes by walking (1.4km).
In general, online real-time information on metro, tramway and buses schedules and locations is available on the following website
https://www.rtm.fr/. In particular, you can get an unlimited 24 hours public transport pass for 5,20 euros and a 72 hours pass for 10.80 euros.
Things to do around the Palais du Pharo and Old Port of Marseille
The Palais du Pharo is ideally located in the Marseille city center and is to a (i) less than 20 minutes walking distance from the Old Port of Marseille and Catalans beach and (ii) less than 40 minutes walking distance from the Notre-Dame de la Garde basilica which offers an outstanding view point on the Marseille bay and Marseille hills, from The Museum of European and Mediterranean Civilisations, Fort Saint-Jean and Marseille Cathedral.
You can find more information on the following website https://www.marseilletourisme.com/
If you stay few more days before or after the conference in Marseille, you will have the opportunity to explore the magnificent nature surrounding the city, such as the Frioul archipelago (that you can reach by a 25 minutes boat trip from the Old Port), or the Calanques National Park, which can be reached by public transport in less than one hour from the Port, and which offers infinite possibilities to hike and swim in shallow water.