Best itinerary this June with 14 year old son?

Camping,, er no idea. Trains are everywhere. History,,Well thats everywhere too. I took my 14 yr old son to Europe and we did a London -Paris trip, Fly into London,, 4-5 days then Eurostar to Paris( which is great , 2.5 hours city center to city center, no airport hassles!) , Paris 4-5 days,, then consider train to Normandy and enjoy 2-3 days there.. In London do not miss London Towers,, in Paris do not miss Invalids War Museum, and my sons both considered the Catacombs a highlight of their visits to Paris. Look up Fat Tire Bike Trips, super fun and easy( I am middle aged woman who hadn't been on a bike for decades!) . It would help if you gave a few more parameters,, like how long is trip, for each major city I always consider a minimum of 4 days, Rome, Paris , London, and I never consider one night stays, and rarely two night stays( tow night stays only actually give you one full day of visiting)

A bit difficult to answer without more specifics, but here are some shout-outs from my 2 boys (now age 12 and 16): Paris--catacombs, sewer tour, Eiffel tower and Versailles (really) London--London Eye, British Museum, London Transport museum Venice-everything Rome-climbing to the roof of St. Peter's, everything else "boring" Lucca-climbed every tower in town, rented bikes to ride around atop the walls Carrara marble mine tour Castles in Austria
Slovenia--Predjama Castle and crazy cave tour in Postojna

Where in Europe will you be travelling? Trains are easy - you can ride them to get anywhere in Europe and even the metro in pretty much every large city is fun and easy to navigate. For history and camping - we enjoyed Rome. We stayed at Camping Village Roma: http://www.ecvacanze.it/en/campingvillageroma Our sons were 13 and 10 at the time, and they loved it. We stayed in a Chalet as there were 4 of us and we didn't have a tent, but if you prefer tenting, then that is an option as well. The campground had its own store, but there was also a large grocery store that was a very easy walk from the campground (just across the highway on a footbridge). There were two pools, beach volleyball, ping pong, etc. so the boys were very happy. There are shuttles available to the Vatican and other tours available through the desk at the campsite. They spoke English very well. From the Vatican, we used a hop-on/hop-off bus to get us around to the major sites. The recorded bus commentary was not very good, but the bus was great for getting us to everywhere important we wanted to go in a day. The Colosseum was amazing, and we enjoyed walking around the Palatino/Forum, etc. as well. Get your tickets at the Palatino first and skip the lines at the Colosseum! The Pantheon and the Trevi Fountain were great sites too. We had some wonderful gelato at Giolitti near the Pantheon:http://www.giolitti.it/english/home.html If you are going in the summer, you should book Vatican tours in advance - we used Angel Tours: http://www.angeltoursrome.com/ Hope that helps!

If he's got a serious train interest I'd recommend the following places in the UK and France: UK: National Railway Museum in York Didcot Railway Centre (easy day trip from London) Bluebell Railway (also easy day trip from London) Severn Valley Railway North Yorkshire Moors Railway
West Somerset Railway In France, if you're in the Alsace area, do a trip to the French national railway museum in Mulhouse (about one hour by train from Strasbourg, also about half an hour from Basel in Switzerland if you're going to Switzerland). Most labelling is in French but they do English audio guides.