In my German high school I took the intensive physics course (Leistungskurs). The university of Bonn organized a so called "Master Class of Particle Physics". A couple of students of each high school would get to attend, and I got to participate.
At the time I did not know much about physics, so I did not know about the divide into theoretical and experimental physics. Also I did not have any opinions about the two sides and would have an idea what (usually humorous) grudges each have against the other. So we had a lecture by the experimentalists about particle physics and how they are detected. Basically we looked at electron-position-collisions and their results into leptons (electron, muon, tau) and hadron jets. We would learn to classify these events. Incidentally I did this later on in the lab course during my studies with a computer program. More accurate and much faster.
On the second day we were sitting in a computer room and were tasked to go through 100 events. Each team of two got different events, and in total we were around 10 groups. We classified around 1000 events on that day. Then later we had a video conference with the organizers of the class from CERN. Michael was a senior employee working in the outreach program, Daniel a PhD student if I recall correctly. During that conference each university would transmit their results and the people at CERN tally them up. In the end we got a result with around ten thousand events.
I am not sure what exactly our result was. I presume that by the counts we looked at the number of quark families or the number of colors. Either way it was an interesting event. And somehow my team got the most events classified correctly and we got a CERN shirt.
After I had finished my compulsory community service in January 2001 I still had a lot of time until my studies would start in September that year. So I contacted the two people from the conference back then and just asked whether I could come for a visit to CERN and look around. I thought that it might be super interesting given that I was going to study physics later on.
Michael said that it would be possible to visit CERN for three days, they had some visitor program which would get me a temporary ID card. I decided to stay a week and also have a look at Geneva while I was there. Supposedly it is a very beautiful city.
When I looked for a hotel for the week I realized that all the ones on the booking sites were already booked out. I am not sure whether they had some special events going on, or CERN was particularly busy that time. I found a hotel on the French side which was not listed on the electronic booking sites. I needed to call there. Using what was left of my French from high school I asked whether they spoke English, which they did not. So I tried to book a room for the time, and it took a while but worked out.
The cheapest flight there was via KLM over Amsterdam. On the map it looks ridiculous to go from Bonn via Amsterdam to Geneva, but I did not mind. From the Airport in Geneva I took the bus and initially waited at the stop into the wrong direction until some helpful bus driver made me aware of that. The coin machines for the tickets in the bus did not give change, one had to go the central station to redeem the change.
The hotel turned out to be a small older hotel, operated by an elderly couple. It looked like the last renovation was quite some ago. And I checked a couple years later and found that it no longer existed. I guess they just retired and gave it up. One time during breakfast I met a scientist who was visiting CERN as well, he told me that this hotel was somewhat of a secret tip among the scientists because it usually had rooms available when the others did not.
For the next three days I would take the bus to the CERN main entrance in the morning. As CERN is directly at the border of France and Switzerland, you cross the border twice a day. It is fairly common for people who work in Geneva to live in France because the cost of living is significantly cheaper there. This also means that you have to have two wallets or at least two compartments for the EUR and CHF coins and bills. If I recall correctly one could often also pay with EUR in Switzerland but would get the change in CHF.
On my first day Michael took me to the reception and let them give me the visitor pass that I needed to get onto the premises. He showed me around various parts of the campus, for instance the ATLAS control room.
As the LHC was in operation there was no opportunity to go down into the detector chambers. But the control room building has the detector painted onto in actual size, so one gets a pretty good idea of the sheer size of that detector.
He also drove me out to the control rooms of the accelerators PS and SPS where the protons used in the LHC are accelerated in multiple stages before they are fast enough to be used in the collisions. One could even hear the transformers have a typical load and unloading sound, he explained the operation and what happened and how that sounds fits to it.
Lunch in the CERN cafeteria is quite a sight in summer. We sat on the deck and had an amazing view to Mont Blanc, a beautiful sight!
On the public premises they have the globe, a mostly wooden construction which is like a museum and shows off particle physics knowledge and also has a theater where they had a stand-up comedy show run by physicists, unfortunately not in the week that I was there. I saw some instance of this show years later online when I was already aware of the playful rivalry between theorists and experimentalists. In that show they introduced another faction, the administrative physicist. They basically don't do any physics at all and are looked down onto by the other two factions. I guess they also look down at the other two because they would not be getting any funding without the administrative work.
This glove looks really amazing at night, they put up quite some impressive lighting.
On the third day Michael was busy but arranged for me to take a look with some PhD students. It is funny that I write this up while I am a PhD student myself. They were preparing some website for students where they could do a few tasks and then have the results checked. I told them that I had some experience with web programming and PHP and they just gave me that task and I had a one day internship there. The program that I wrote is trivial in hindsight, it just reads the expected results from a CSV file and compares it to the ones that the users have entered. But it kept me busy for a while and I was happy to get a feeling of the actual work being done there. In retrospect I must say that I had no idea and I just could not have imagined what I am doing now while I was there back then.
As the maximum visiting time was there days, I spent the other days in central Geneva. My hotel on the west side in France was not connected to the tram, so I took the bus or my feet to CERN and then the train to the main station.
Geneva has a central lake with a fountain, which is quite the sight. I'm currently reading the book by Snowden and he describes how he sits on the banks of the lake. This reminded me of myself sitting there and writing about this journey.
Close to the lake I saw a clock made out of flowers, that looked like a lot of work! Geneva has a tradition of clock and watch manufacturing, therefore the flower clock does not come unprecedented.
In general Geneva is a rather rich or expensive city. One can easily see that when ordering some food. I had some lasagna in an Italian restaurant there and although I am not sure I would say that I payed more than 20 EUR for it. Coincidentally I saw the waiter in the tram towards France in the evening, I presume that he lives in France where it is cheaper.
There are many very fancy hotels with tons of fancy cars there. I played with the thought of spending a night there, but they were prohibitively expensive and I rather looked at them from the outside.
While walking through the city I found many small parts all over. This was really nice in the summer as one could relax in a part before continuing to stroll through the city. Together with the lake this city has a really nice climate.
Although Geneva hosts some large institutions like the UN, all I could do is to look at them from the outside. They all have really fancy buildings, but without getting inside there was not much interesting to do.
All in all it has been a nice trip with some insights to CERN and also an impression of a beautiful but expensive city. During my course of study I found myself not drawn to experimental particle physics and never actually went for CERN to do actual research on my own. A few of my colleagues have stayed at CERN, but I never did any of the detector or experiment stuff there. So in retrospect this visit might now have primed me for experimental particle physics, yet still I increased my interest in physics.