An oldie but a goodie..
When the benei yisrael travelled, the mishkan was not re-assembled in the same place that it was dismantled.
Nevertheless there is an opinion in shabbos 31 that with regards to the melacha of soser (destroying a building), you are only chayav if it is soser al menos livnos bimekomo – you will rebuild the building in the same place.
Seeing as we learn the 39 melachos from the mishkan – and seeing that reagrding the mishkan, the structure was not rebuilt in the same place – how could this be a limitation in the melacha?
The answer is that seeing as the benei yisroel travelled with the shechina – they were always ‘in the same place’ – next to the shechina. Their physical location was inconsequential to them compared to their closeness to Hashem.