In the center of European Russia, 8 hours by car or train from St. Petersburg, 4 hours by plane from London, 2.5 hours by plane from Berlin (or 36 hours by train), 6 hours by plane from India, 6 days by Trans-Siberian train from Beijing.
The main historical core of Moscow is Kremlin which is located in the core of the city. Tverskaya street, which is the main avenue of the city, starts from the Kremlin and heads north to become Leningradskoye Shosse, which leads directly to St. Petersburg (750km). Moscow has a radial structure, and the Garden Ring road defines the center of the city. A smaller Boulevard Ring defines the city's downtown.
To be able to find the right building on any street, it's useful to know that in Moscow house numbering starts from the center. Also, the odd-number houses are located to the left, and the even-number houses - to the right. So, if you're looking for Tverskaya st., #2, for example, it will be located very close to the Kremlin (which is the most central place in Moscow), on your right-hand side (if you turn your back to the Kremlin).