Omg! Please tell me there are sites of these left over to explore!? Thank you
Switzerland was a neutral country in WW1, so it seems unlikely there would be WW1 trenches in or near Basel, which is a border town.
Not in the location you want but i believe that the best trench exhibit along with dugout exhibit is at Passchendale museum in Belgium.
If you want to see remnants or preserved examples of trenches, go to northern France in the Pas-de-Calais area. The exact place is Vimy, near Arras (Gen. HQ for the British), where the Canadian memorial is located. You'll see which areas are cordoned off, off limits, where the trenches were.. The area from Arras south to Amiens on the Somme is dotted with green and white signs and tall white crosses indicating British and Commonweath military cemeteries from WW 1.
Thanks to the history buffs.
It is untrue to say that because Switzerland was neutral there were no trenches.The Swiss army occupied the border to prevent either army taking a shortcut through neutral Switzerland (which is exactly what the Germans did throught neutral Belgium at the start of the war).
The pre-1920 border, and hence the trenches, were well west of Basel. As the previous poster says the pre-1920 French-German border met the Swiss border at Pfefferhouse.
There is a small monument to these soldiers at Grellingen a few Km south-west of Basel. Worth stopping if you are passing, otherwise not.
On Tullingen hill, overlooking Basel on the German side of the Rhine, there is a monument put up after the war by the soldiers who defended Hüningen during the war. The poignant point is you can look down from the hill on Hüningen. Hüningen is part of Alsace, which was German before 1920, and which these soldiers had defended throught the war without having to fire a shot, and then had to give up in the treaty of Versailles.
Again not really worth a visit.
But finally I can recommend Hartmannswillerkopf. This is an imposing memorial on the "Route de crête" north-west of Mulhouse. The Route de crête is worth the drive in itself (no public transport). This was the site of some major fighting and is a large graveyard and memorial.
"The pre-1920 border, and hence the trenches, were well west of Basel."
Thanks for the extra information.
You've also confirmed the correctness of the answers already given: The original question was whether there were trenches in or around Basel, and the answer was no.