  The quasar 3C345 is one of the best examples of extragalactic jet with
superluminal components moving on helical paths. To get better constraints on
the jet physics, we have imaged the source at the highest possible resolution,
using mm-VLBI and space-VLBI observations. We observed 3C345 at 5 different
epochs so far (1 epoch with 3-mm ground VLBI, and 4 epochs with space VLBI at
6cm and 18cm). These measurements expand significantly our ongoing monitoring
of 3C345. In this contribution, we discuss the properties of the jet and its
moving components in the immediate vicinity of the core (<3mas).
