The area known as the Mozhaisk Kremlin is located on the western edge of the city although the original kremlin walls no longer stand.   The first wooden fortifications here were erected in the 12th century and over time faced the armies of Tudan in 1293, Prince Yuri Danilovich of Moscow in 1303, Grand Duke Algirdas of Lithuania in 1341 and 1370, Toktamysh in 1382 and finally Prince Władysław of Poland in 1618.  After this the wooden defences were replaced with stone walls, which had been demolished by the 18th century.

St Nicholas' Cathedral

Located within the kremlin is the beautiful St Nicholas' Cathedral which was built between 1779 and 1812 and even incorporated parts of the old kremlin's walls in its construction. The cathedral is a stunning example of Russian Gothic style and is the most famous site in Mozhaisk itself. As it is built on a hill, it is visible from afar when approaching the city on the Old Smolensk Road. The cathedral was closed in 1933 and was heavily damaged in the Second World War; its dome was never rebuilt. Later it was used as a fabric factory, only eventually being returned to the Russian Orthodox Church in 1994.

Ss Peter and Paul's Church

Standing next to St Nicholas' Cathedral is the simple Ss Peter and Paul's Church which is also sometimes referred to as the Old St Nicholas' Cathedral. The present building was built in the mid-19th century to replace the city's former 15th century cathedral which once stood here. Having been closed in the 1930s, it was used as a museum since the 1960s, and returned to the Church in 2003. Although rather plain on the outside, especially compared to its wonderful neighbour, inside it boasts new and colourful frescoes.