My original plan was three days in Berlin and four in Switzerland. A visa agent told me I needed to spend longer in Germany to apply there, so I added a day across western Germany. With the original itinerary, I might not have got past the VFS Global counter, let alone been approved 😎

After getting my visa, I could go as planned, the consulate usually only checks entry and exit, but because this is my first time going to Europe, I didn't expect much, just go 😝

Dortmund, Cologne and Frankfurt in a day — photo 1
The boat leaves at 5:46, but I have to wake up from 5:00 to prepare, although in the dorm room but still to wake up, people wake up also pik how can be:)))
When we got to the reception, there were some security guys there, they said we just had to pay with a card, and then we walked to the train station.
Dortmund, Cologne and Frankfurt in a day — photo 2

5:33 a.m. at Hamburg Hbf.

Dortmund, Cologne and Frankfurt in a day — photo 3

Waiting for the train at the station.

Dortmund, Cologne and Frankfurt in a day — photo 4

The train ran on time, although this wasn’t the fastest an ICE could go. I’d never been on a high-speed train doing more than 150 km/h in China. Maybe I just hadn’t paid for one of the fancy ones.

Dortmund, Cologne and Frankfurt in a day — photo 5
The golden cabbage season in Europe, this part near Bremen, outside is better, because the train is going so fast, just take a photo and the train passes 😇
Dortmund, Cologne and Frankfurt in a day — photo 6
Dortmund, Cologne and Frankfurt in a day — photo 7
At Dortmund Hbf station, walking around to buy food with the witch, and finding ticket machines, I want to take the RE train but the machine does not show the stop I want to go to so buy a ticket for the subway.
To Remydamm station walk is quite far to reach the stadium, I walked around the stadium to find the entrance, the sun is strong.
Dortmund, Cologne and Frankfurt in a day — photo 8
Security checked my backpack. When they asked for my ticket I didn’t have one, so I bought it at the counter and tapped my credit card for €9.
Dortmund, Cologne and Frankfurt in a day — photo 9
The largest stadium in Germany, with a capacity of over 81,000 seats.
There will be a one-way passage for tourists from the entrance to the exit, and once they leave, the security officers there will not let them back.
Dortmund, Cologne and Frankfurt in a day — photo 10
After visiting, take the train back to the central station, there is a RE station closed, station Remydamm only gets people off but not up, so walk about 700 meters to the nearest Westfalenpark underground station.
Dortmund, Cologne and Frankfurt in a day — photo 11

I see the peony on the green grass :D
Dortmund, Cologne and Frankfurt in a day — photo 12
At noon, the DB tickets would be too expensive, so they switched to the FlixTrain to Cologne. Because the cheap ticket is 12.89 euros, it's crowded, the train feels like it's not air-conditioned, there's nobody checking tickets on this section.
At the place, I walked out to find a restaurant and saw a sea called Pho Hung so I went in to eat, the guy knew that Vietnamese should cook saltier than usual but I tried not to eat all the toast because salty 😝 I want to eat even more bread and I'm full. A plate of toasted rice over 420k, a piece of bread over 210k 😈
Dortmund, Cologne and Frankfurt in a day — photo 13
The church is 157 meters high, going inside cool, because the next train to Frankfurt has a lot of time so I sat in the church rest about 30 ', after going around, wherever you can go, you go. I thought there was a tunnel maze down there, but it's blocked at the tunnel entrances.
Dortmund, Cologne and Frankfurt in a day — photo 14
The picture was taken inside the church.
Dortmund, Cologne and Frankfurt in a day — photo 15
The last one, up to nearly 300 km/h, the distance by car from Cologne to Frankfurt is about 200 km which the train runs 1h23' to reach. This section also bought a cheap ticket of 12.99 euros, telling how much money I saved on this trip by buying a train ticket.
I walked out of the station to Pho Hung to buy some bread, I went a little bit wrong, so I searched maps, and I remembered I was in Cologne.
Dortmund, Cologne and Frankfurt in a day — photo 16
I took the tram back to the hostel. I still don’t quite understand this part. I stood at the right stop and thought I’d boarded the right tram, but it headed for the airport :D I got off when it was clearly going the wrong way and walked a kilometre and a half to a stop on the route I’d paid for.
Dortmund, Cologne and Frankfurt in a day — photo 17
Dortmund, Cologne and Frankfurt in a day — photo 18
It's 8:00pm, people are walking, doing sports, picnics are busy, my daughter is also feeling cooler in Berlin, I'm waiting for the tram 30' and all I see are super cars 🚗 
Dortmund, Cologne and Frankfurt in a day — photo 19
Because we waited too long and didn't see the tram coming, we had to walk another bit to the nearest stop.
Dortmund, Cologne and Frankfurt in a day — photo 20
I arrived in Frankfurt at 7:30, if I was right, tram 11 only took 23' to get back to the hostel, in fact it took me 2:30 to get back.
At the reception desk there are three machines for automatic check-in, because I put the name in Vietnamese so it was wrong, ask the staff there check-in for.
There was live music, pool, table football and space to work.
And I'm going to go to bed after I've taken a shower and I'm gonna close my eyes 😎😎😎