Since 1983 I have participated in a number of national and international conferences on Ancient History in the Netherlands, Europe, and East Asia, and given numerous guest lectures and talks outside Leiden for students, colleagues, and/or the wider public in various places in the Netherlands and Europe, as well as in Japan (Tokyo) and Chine (Beijin, Shanghai, Tianjin, Chengdu, Wuhan, Lioacheng) on topics of Ancient History, comparative history or the legacy of the Ancient world, in particular about:

• Ancient Military History
• Sparta
• Alexander and the Hellenistic World
• Early Christianity
• The later Roman Empire and Byzantium
• The Ancient Greeks and India
• The empire and civilization of Ankor in South East Asia

From 2004 till 2024 I have been active as a tour guide on some cultural tours – numbering one to three annually, except for the years 2020-2021 – to the following destinations:

• Ravenna, Padua and Venice,
• Southern Italy (from Tarent to Naples)
• Sicily
• Crete
• Athens, Delphi and the Peloponnese
• Attica and Boeotia
• Northern Greece
• Cycladic Islands of Greece
• Rhodes, Patmos, Cos and Samos
• Cyprus
• Turkey (Istanbul, Troy, Pessinus, Ankara, Hatussa/Boghazköy, Assos to Priëne)
• Eastern Thailand, South-Laos and Cambodia