Isfahan has a population of approximately 1.7 million, making it the third largest city in Iran after Tehran and Mashhad, having been once one of the largest cities in the world. Isfahan is also called "Esfahan" today. This city has had important roles during the Persia(Iran)'s history since it's located in the central part of Iran. It is thus an intersection of the two principal north-south and east-west routes that cross Iran. Moreover, her location has been keeping her safe from invasions. in the 16th and 17th centuries. Isfahan flourished under the Safavid Dynasty and has been the capital of Persian culture, civilization, and industry since then.
You can start your visit with Naqsh-e-Jahan Square, walk across Charbaq Street, then visit the famous bridges "Khaju" and "Siosepol". I myself recommend that you visit the mentioned sights on foot so that you can get acquainted with the city's beautiful atmosphere. Don't worry! it'd be a piece of cake and full of joy! The nice thing about Esfahan is that despite her being a big crowded city, her sights are easy to access and located near each other and various means of transportation are also available.
Please don't hesitate to contact your Isfahan tour-guide, Alireza! Depending on my schedule, I can also accompany you to Yazd.
Best wishes :)