If you want to come here by car, take the A3 Motorway to the exit Leverkusen. Then follow the Willy-Brandt-Ring to Bayer Werk. Before the Leverkusen plant, turn left into Friedrich-Ebert-Straße and take this to the sign "Tor 2". Turn right. Visitor parking is directly across from the guardhouse for "Tor 2".
Take the S-Bahn train to the station "Bayerwerk". Walk along Otto-Bayer-Straße to Düsseldorfer Straße, then turn right. After several hundred meters, you will come to Kaiser-Wilhelm-Allee; take this to "Tor 2".
A detailed trip diagramme is available to download here.