We present ALMA multiwavelength observations of the protoplanetary disk around the nearby (d~100pc) young solar analog MP Mus (PDS 66). These observations at 0.89mm, 1.3mm, and 2.2mm have angular resolutions of ~1", 0.05", and 0.25", respectively, and probe the dust and gas in the system with unprecedented detail and sensitivity. The disk appears smooth down to the 4au resolution of the 1.3mm observations, in contrast with most disks observed at comparable spatial scales. The dust disk has a radius of 60au, a dust mass of 0.14M_Jup_, and a mm spectral index <2 in the inner 30au, suggesting optically thick emission from grains with high albedo in this region. Several molecular gas lines are also detected extending up to 130au, similar to small grains traced by scattered light observations. Comparing the fluxes of different CO isotopologues with previous models yields a gas mass of 0.1-1M_Jup_, implying a gas to dust ratio of 1-10. We also measure a dynamical stellar mass of M_dyn_=1.30M_{sun}_ and derive an age of 7-10Myr for the system. The survival of large grains in an evolved disk without gaps/rings is surprising, and it is possible that existing substructures remain undetected due to optically thick emission at 1.3mm. Alternatively, small structures may still remain unresolved with the current observations. Based on simple scaling relations for gap-opening planets and gap widths, this lack of substructures places upper limits to the masses of planets in the disk as low as 2M_{Earth}_-0.06M_Jup_ at r>40au. The lack of mm emission at radii r>60au also suggests that the gap in scattered light between 30-80au is likely not a gap in the disk density, but a shadow cast by a puffed-up inner disk.