Italy: Regatta of the Four Ancient Maritime Republics (varies : Pisa/Venice/Amalfi/Genoa). Florence, Festival of Saint John – parades, dances and Calcio Storico, wild and violent 15thC costumed football matches, June 24th.
England: Trooping the Colour, London (Queen’s birthday parade) June 17.
Wimbledon Tennis Tournament – the most prestigious tennis event in the world.
Isle of Man TT (motorcycle) Races, May/June.
Glyndbourne Festival Opera (in a Stately Home outside London), late May-early July. Stonehenge summer equinox festivites, June 20st-21st. A free all nighter with a zillion wackos.
France: Fete de la Musique, in Paris. Free! A monster musical celebration all over this lovely city. Professionals mix with amateurs playing different sounds in different locations, June 21st.
Chaumont Garden Festival – thirty wonderful and sometimes wacky show gardens around a perfect chateau (castle), every year May- October.
Netherlands: The Holland Festival (varied arts), Amsterdam and The Hague, all June.
Hungary: Sopron festival Weeks, ancient music and dance, June & July, Sopron.
Austria: Vienna International Festival from mid-May to mid-June (wide range of arts).
Greece: Athens Festival, drama and music in ancient theatres. June-Sept.
Denmark: Roskilde Festival, north Europe’s largest rock music festival, late June-early July.
Germany, Christopher Street Day in Berlin – a monster Gay Pride parade and street party.
Turkey: International Istanbul Festival of Arts, most of June.
Russia, Stars of the White Nights Festival. Primarily opera and ballet.
Belgium, Hainaut, The Golden Chariot and Battle of Lumecon – Saint George fights the dragon and everybody pushes a vast and holy chariot around town, June 6th.
Ireland, Dublin ++, Great Irish Houses Festival – music in great Irish houses, mostly Dublin, plus counties Wicklow and Kildare.
Also see European Festivals or Arts Festivals for suggestions, information and dates.