The low-lying even-parity energy levels and wave functions of the even isotopes of tungsten, osmium and platinum are calculated within the framework of Bohr's collective Hamiltonian. The six kinetic energy functions and the potential energy function which enter the Hamiltonian, and which determine the coupling between rotational motion, β-vibrations and γ-vibrations, are derived microscopically by using the pairing-plus-quadrupole model of residual interactions. Coupling between the three kinds of motion are treated exactly, and a numerical method is used to solve the Schrödinger equation. At the low- A end of the W-Os-Pt region, there are large deviations from the rotational model; the β-γ-bands are strongly mixed. At the high- A end, there are large deviations from the phonon model; the wave functions are smeared over all possible shapes, and a large, positive quadrupole moment of the first 2 + state of 196Pt is predicted. Many energy levels, B(E2) values, quadrupole moments, B(M1) value, magnetic moments, electric monopole transitions and nuclear shape fluctuations are also predicted.