How do I prove house existed? 

I am in the process of trying to build a house in Campbell, CA.  The City is assessing me a $16,000 fee for the local parks because they think a house never existed on my lot previously.  But there was a house on the lot until the state (CAL TRANS) purchased the lot, tore down the existing house and some 10 years later sold the lot to me.  Then the lot was annexed from the county to the city.  My question is, is there any way I can prove to them the house existed before?  

Thanks in advance for any replies

-Fitz