1. A method of determining a geometrical configuration of an interconnect structure of a test structure, the method comprising: Obtaining simulation data correlating capacitance data, resistance data and geometrical configuration data for a plurality of interconnect structures having different geometrical configurations by: determining a capacitance value and a resistance value for each of the plurality of geometrical configurations of an interconnect structure in an integrated circuit (IC) design using a field solver and simulation analytical equations, increasing a number of data points in the simulation data by interpolating the capacitance value and the resistance value of the different geometrical configurations, saving the simulation data in a database, and allowing access to the database; Measuring a capacitance value and a resistance value from the interconnect structure of the test structure by: obtaining delay information of the interconnect structure from at least one ring oscillator coupled to the interconnect structure, and determining the capacitance value and the resistance value based on the delay information; and Determining the geometrical configuration of the interconnect structure by comparing the capacitance value and the resistance value to capacitance data and resistance data of the simulation data for the correlated geometrical configuration data.