Here, we investigate in detail the low temperature structural and physical properties of the trilayer nickelates R4Ni3O10 (R = La, Pr and Nd) using resistivity, thermopower, thermal conductivity, specific heat, highresolution synchrotron powder X-ray diffraction, and thermal expansion experiments. We show that all three compounds crystallize with a monoclinic symmetry (space group P 21/a, Z = 4), and undergo a metal-to-metal transition (MMT) near TMMT = 135 K (La), 156 K (Pr) and 160 K (Nd). Upon cooling below MMT, the lattice parameters in each case show a distinct anomaly at TMMT, however, without any lowering of the lattice symmetry. Unambiguous signatures of MMT are also observed in magnetic and thermal measurements, suggesting that there is a strong coupling between the electronic, magnetic and structural degrees of freedom in these nickelates. Analysis of thermal expansion yields hydrostatic pressure dependence of MMT in close agreement with previous experimental results. In Pr4Ni3O10, we show that the 9-fold coordinated Pr 3+ ions in the rocksalt (RS) layers have a crystal field (CF) split doublet ground state with possible antiferromagnetic ordering near 5 K. In contrast to this, the Pr 3+ ions in the perovskite-block (PB) layers with a 12-fold coordination seems to exhibit a non-magnetic singlet ground state. In Nd4Ni3O10, on the other hand, the CF ground state of Nd 3+ ions in both RS and PB layers is a Kramers doublet. The heat capacity of Nd4Ni3O10 shows a pronounced Schottky-like anomaly near T = 35 K; and, an upturn below 10 K due to the presence of short-range correlations between the Nd moments. However, no signs of long-range ordering could be found down to 2 K despite a sizeable value of θp ∼ −40 K. The strongly suppressed magnetic long-range ordering in both R = Pr and Nd suggests the presence of strong magnetic frustration in these compounds. The low-temperature resistivity shows a − √ T dependence, and the electronic term in the specific heat of Nd4Ni3O10 is falsely inflated due to the overwhelming Schottky contribution. These observations rule out the alleged heavy fermion behavior recently reported for Nd4Ni3O10.