 Complete the following phrase:  The Isartor was constructed in 1337 within the scope of the enlargement of Munich and the construction of the second city wall between 1285 and 1337 which was completed under the Emperor Louis IV. The gate first consisted of a main gate tower. Only with the construction of the moat wall of the gate tower the two flanking side towers were added and served as barbican. The Isartor is today the only medieval gate in Munich which has conserved its medium main tower and the restoration in 1833-35 by Friedrich von Gärtner has recreated the dimensions and appearance close to the original structure. The frescos, created in 1835 by Bernhard von Neher, depict the victorious return of Emperor Louis after the 